MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 8666 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 1551. |
What is the slope of the tangent to the curve\[y={{\sin }^{-1}}({{\sin }^{2}}x)at\,\,x=0\]? |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | None of these |
| Answer» B. 1 | |
| 1552. |
The range of the function\[f(x)=2\sqrt{x-2}+\sqrt{4-x}\] is |
| A. | \[\left( \sqrt{2},\sqrt{10} \right)\] |
| B. | \[\left[ \sqrt{2},\sqrt{10} \right)\] |
| C. | \[\left( \sqrt{2},\sqrt{10} \right]\] |
| D. | \[\left[ \sqrt{2},\sqrt{10} \right]\] |
| Answer» E. | |
| 1553. |
If at any instant t, for a sphere, r denotes the radius, S denotes the surface area and V denotes the volume, then what is \[\frac{dV}{dt}\] equal to? |
| A. | \[\frac{1}{2}S\frac{dr}{dt}\] |
| B. | \[\frac{1}{2}r\frac{dS}{dt}\] |
| C. | \[r\frac{dS}{dt}\] |
| D. | \[\frac{1}{2}{{r}^{2}}\frac{dS}{dt}\] |
| Answer» C. \[r\frac{dS}{dt}\] | |
| 1554. |
If \[x\text{ }cos\theta +y\text{ }sin\text{ }\theta =2\] is perpendicular to the line\[x-y=3\], then what is one of the value of\[\theta \]? |
| A. | \[\pi /6\] |
| B. | \[\pi /4\] |
| C. | \[\pi /2\] |
| D. | \[\pi /3\] |
| Answer» C. \[\pi /2\] | |
| 1555. |
The radius of a circle is uniformly increasing at the rate of 3 cm/s. What is the rate of increase in area, when the radius is 10 cm? |
| A. | \[6\pi \,c{{m}^{2}}/s\] |
| B. | \[10\pi \,c{{m}^{2}}/s\] |
| C. | \[30\pi ;c{{m}^{2}}/s\] |
| D. | \[60\,\pi \,c{{m}^{2}}/s\] |
| Answer» E. | |
| 1556. |
The straight line \[\frac{x}{a}+\frac{y}{b}=2\] touches the curve \[{{\left( \frac{x}{a} \right)}^{n}}+{{\left( \frac{y}{b} \right)}^{n}}=2\] at the point (a, b) for |
| A. | n = 1, 2 |
| B. | n = 3, 4, -5 |
| C. | n = 1, 2, 3 |
| D. | Any value of n |
| Answer» E. | |
| 1557. |
The number of tangents to the curve \[{{x}^{3/2}}+{{y}^{3/2}}=2{{a}^{3/2}},\,\,\,a>0,\] which are equally inclined to the axes, is |
| A. | 2 |
| B. | 1 |
| C. | 0 |
| D. | 4 |
| Answer» C. 0 | |
| 1558. |
The maximum area of a right angled triangle with hypotenuse h is: |
| A. | \[\frac{{{h}^{2}}}{2\sqrt{2}}\] |
| B. | \[\frac{{{h}^{2}}}{2}\] |
| C. | \[\frac{{{h}^{2}}}{\sqrt{2}}\] |
| D. | \[\frac{{{h}^{2}}}{4}\] |
| Answer» E. | |
| 1559. |
The distance of the point on \[y={{x}^{4}}+3{{x}^{2}}+2x\] which is nearest to the line \[y=2x-1\] is |
| A. | \[\frac{2}{\sqrt{5}}\] |
| B. | \[\sqrt{5}\] |
| C. | \[\frac{1}{\sqrt{5}}\] |
| D. | \[5\sqrt{5}\] |
| Answer» D. \[5\sqrt{5}\] | |
| 1560. |
If \[a=2i+j+2k\] and \[b=5i-3j+k,\] then the projection of b on a is [Karnataka CET 2002] |
| A. | 3 |
| B. | 4 |
| C. | 5 |
| D. | 6 |
| Answer» B. 4 | |
| 1561. |
The projection of a along b is [RPET 1995] |
| A. | \[\frac{\mathbf{a}\,.\,\mathbf{b}}{|\mathbf{a}|}\] |
| B. | \[\frac{\mathbf{a}\,\times \,\mathbf{b}}{|\mathbf{a}|}\] |
| C. | \[\frac{\mathbf{a}\,.\,\mathbf{b}}{|\mathbf{b}|}\] |
| D. | \[\frac{\mathbf{a}\,\times \,\mathbf{b}}{|\mathbf{b}|}\] |
| Answer» D. \[\frac{\mathbf{a}\,\times \,\mathbf{b}}{|\mathbf{b}|}\] | |
| 1562. |
If vector \[\mathbf{a}=2\mathbf{i}-3\mathbf{j}+6\mathbf{k}\] and vector \[\mathbf{b}=-2\mathbf{i}+2\mathbf{j}-\mathbf{k},\] then \[\frac{\text{Projection of vector }\mathbf{a}\text{ on vector }\mathbf{b}}{\text{Projection of vector }\mathbf{b}\text{ on vector }\mathbf{a}}=\] [MP PET 1994, 99; Pb. CET 2000] |
| A. | \[\frac{3}{7}\] |
| B. | \[\frac{7}{3}\] |
| C. | 3 |
| D. | 7 |
| Answer» C. 3 | |
| 1563. |
The projection of vector \[2\mathbf{i}+3\mathbf{j}-2\mathbf{k}\] on the vector \[\mathbf{i}+2\mathbf{j}+3\mathbf{k}\] will be [RPET 1984, 90, 97, 99; Karnataka CET 2004] |
| A. | \[\frac{1}{\sqrt{14}}\] |
| B. | \[\frac{2}{\sqrt{14}}\] |
| C. | \[\frac{3}{\sqrt{14}}\] |
| D. | \[\sqrt{14}\] |
| Answer» C. \[\frac{3}{\sqrt{14}}\] | |
| 1564. |
Let \[\mathbf{b}=3\mathbf{j}+4\mathbf{k},\,\,\mathbf{a}=\mathbf{i}+\mathbf{j}\] and let \[{{\mathbf{b}}_{1}}\] and \[{{\mathbf{b}}_{2}}\] be component vectors of b parallel and perpendicular to a. If \[{{\mathbf{b}}_{1}}=\frac{3}{2}\mathbf{i}+\frac{3}{2}\mathbf{j}\], then \[{{\mathbf{b}}_{2}}=\] [MP PET 1989] |
| A. | \[\frac{3}{2}\mathbf{i}+\frac{3}{2}\mathbf{j}+4\mathbf{k}\] |
| B. | \[-\frac{3}{2}\mathbf{i}+\frac{3}{2}\mathbf{j}+4\mathbf{k}\] |
| C. | \[-\frac{3}{2}\mathbf{i}+\frac{3}{2}\mathbf{j}\] |
| D. | None of these |
| Answer» C. \[-\frac{3}{2}\mathbf{i}+\frac{3}{2}\mathbf{j}\] | |
| 1565. |
The component of \[\mathbf{i}+\mathbf{j}\] along \[\mathbf{j}+\mathbf{k}\] will be |
| A. | \[\frac{\mathbf{i}+\mathbf{j}}{2}\] |
| B. | \[\frac{\mathbf{j}+\mathbf{k}}{2}\] |
| C. | \[\frac{\mathbf{k}+\mathbf{i}}{2}\] |
| D. | None of these |
| Answer» C. \[\frac{\mathbf{k}+\mathbf{i}}{2}\] | |
| 1566. |
A vector of magnitude 14 lies in the xy-plane and makes an angle of \[{{60}^{o}}\] with x-axis. The components of the vector in the direction of x-axis and y-axis are |
| A. | \[7,\,\,7\sqrt{3}\] |
| B. | \[7\sqrt{3},\,\,7\] |
| C. | \[14\sqrt{3},\,\,14/\sqrt{3}\] |
| D. | \[14/\sqrt{3},\,\,14\sqrt{3}\] |
| Answer» B. \[7\sqrt{3},\,\,7\] | |
| 1567. |
If a and b are two non-zero vectors, then the component of b along a is [MP PET 1991] |
| A. | \[\frac{(\mathbf{a}\,.\,\mathbf{b})\,\mathbf{a}}{\mathbf{b}\,.\,\mathbf{b}}\] |
| B. | \[\frac{(\mathbf{a}\,.\,\mathbf{b})\,\mathbf{b}}{\mathbf{a}\,.\,\mathbf{a}}\] |
| C. | \[\frac{(\mathbf{a}\,.\,\mathbf{b})\,\mathbf{b}}{\mathbf{a}\,.\,\mathbf{b}}\] |
| D. | \[\frac{(\mathbf{a}\,.\,\mathbf{b})\,\mathbf{a}}{\mathbf{a}\,.\,\mathbf{a}}\] |
| Answer» E. | |
| 1568. |
If a has magnitude 5 and points north-east and vector b has magnitude 5 and points north-west, then \[|\,\,\mathbf{a}-\mathbf{b}\,\,|\,=\] [MNR 1984] |
| A. | 25 |
| B. | 5 |
| C. | \[7\sqrt{3}\] |
| D. | \[5\sqrt{2}\] |
| Answer» E. | |
| 1569. |
If the vectors \[3i+\lambda \,j+k\] and \[2i-j+8k\] are perpendicular, then \[\lambda \] is [Kerala (Engg.) 2002] |
| A. | ? 14 |
| B. | 7 |
| C. | 14 |
| D. | 1/7 |
| Answer» D. 1/7 | |
| 1570. |
If \[4i+j-k\] and \[3i+mj+2k\] are at right angle, then \[m=\] [Karnataka CET 2002] |
| A. | ? 6 |
| B. | ? 8 |
| C. | ? 10 |
| D. | ? 12 |
| Answer» D. ? 12 | |
| 1571. |
If \[\mathbf{a}=\mathbf{i}-2\mathbf{j}\] and \[\mathbf{b}=2\mathbf{i}+\lambda \mathbf{j}\] are parallel, then \[\lambda \] is [RPET 1996] |
| A. | 4 |
| B. | 2 |
| C. | ? 2 |
| D. | ? 4 |
| Answer» E. | |
| 1572. |
If \[ai+6j-k\] and \[7i-3j+17k\] are perpendicular vectors, then the value of a is [Karnataka CET 2001] |
| A. | 5 |
| B. | ? 5 |
| C. | 7 |
| D. | \[\frac{1}{7}\] |
| Answer» B. ? 5 | |
| 1573. |
The vector \[\frac{1}{3}\,(2\mathbf{i}-2\mathbf{j}+\mathbf{k})\] is [IIT Screening 1994] |
| A. | A unit vector |
| B. | Makes an angle \[\frac{\pi }{3}\] with the vector \[2i-4\mathbf{j}+3\mathbf{k}\] |
| C. | Parallel to the vector \[-\mathbf{i}+\mathbf{j}-\frac{1}{2}\mathbf{k}\] |
| D. | Perpendicular to the vector \[3\mathbf{i}+2\mathbf{j}-2\mathbf{k}\] |
| Answer» E. | |
| 1574. |
Which of the following is a true statement [Kurukshetra CEE 1996] |
| A. | \[(\mathbf{a}\times \mathbf{b})\times \mathbf{c}\] is coplanar with c |
| B. | \[(\mathbf{a}\times \mathbf{b})\times \mathbf{c}\] is perpendicular to a |
| C. | \[(\mathbf{a}\times \mathbf{b})\times \mathbf{c}\] is perpendicular to b |
| D. | \[(\mathbf{a}\times \mathbf{b})\times \mathbf{c}\] is perpendicular to c |
| Answer» E. | |
| 1575. |
If the vectors \[a\mathbf{i}+2\mathbf{j}+3\mathbf{k}\] and \[-\mathbf{i}+5\mathbf{j}+a\mathbf{k}\] are perpendicular to each other, then \[a=\] [MP PET 1996] |
| A. | 6 |
| B. | ? 6 |
| C. | 5 |
| D. | ? 5 |
| Answer» E. | |
| 1576. |
If the vectors \[a\mathbf{i}+b\mathbf{j}+c\mathbf{k}\] and \[p\mathbf{i}+q\mathbf{j}+r\mathbf{k}\] are perpendicular, then [RPET 1989] |
| A. | \[(a+b+c)\,(p+q+r)=0\] |
| B. | \[(a+b+c)\,(p+q+r)=1\] |
| C. | \[ap+bq+cr=0\] |
| D. | \[ap+bq+cr=1\] |
| Answer» D. \[ap+bq+cr=1\] | |
| 1577. |
If \[\mathbf{a}=2\mathbf{i}+4\mathbf{j}+2\mathbf{k}\] and \[\mathbf{b}=8\mathbf{i}-3\mathbf{j}+\lambda \mathbf{k}\] and \[\mathbf{a}\,\bot \,\mathbf{b},\] then value of \[\lambda \] will be [RPET 1995] |
| A. | 2 |
| B. | ? 1 |
| C. | ? 2 |
| D. | 1 |
| Answer» D. 1 | |
| 1578. |
The value of \[\lambda \] for which the vectors \[2\lambda \mathbf{i}+\mathbf{j}-\mathbf{k}\] and \[2\mathbf{j}+\mathbf{k}\] are perpendicular, is [MP PET 1992] |
| A. | None |
| B. | ? 1 |
| C. | 1 |
| D. | Any value |
| Answer» B. ? 1 | |
| 1579. |
If \[|\mathbf{a}|+|\mathbf{b}|\,=\,|\mathbf{c}|\] and \[\mathbf{a}+\mathbf{b}=\mathbf{c},\] then the angle between a and b is |
| A. | \[\frac{\pi }{2}\] |
| B. | \[\pi \] |
| C. | 0 |
| D. | None of these |
| Answer» D. None of these | |
| 1580. |
The unit normal vector to the line joining \[\mathbf{i}-\mathbf{j}\] and \[2\,\mathbf{i}+3\,\mathbf{j}\] and pointing towards the origin is [MP PET 1989] |
| A. | \[\frac{4\,\mathbf{i}-\mathbf{j}}{\sqrt{17}}\] |
| B. | \[\frac{-4\,\mathbf{i}+\mathbf{j}}{\sqrt{17}}\] |
| C. | \[\frac{2\,\mathbf{i}-3\,\mathbf{j}}{\sqrt{13}}\] |
| D. | \[\frac{-\,2\,\mathbf{i}+3\,\mathbf{j}}{\sqrt{13}}\] |
| Answer» C. \[\frac{2\,\mathbf{i}-3\,\mathbf{j}}{\sqrt{13}}\] | |
| 1581. |
If \[l\,\mathbf{a}+m\,\mathbf{b}+n\,\mathbf{c}=\mathbf{0},\] where \[l,\,m,\,\,n\] are scalars and a, b, c are mutually perpendicular vectors, then |
| A. | \[l=m=n=1\] |
| B. | \[l+m+n=1\] |
| C. | \[l=m=n=0\] |
| D. | \[l\ne 0,\,\,m\ne 0,\,\,n\ne 0\] |
| Answer» D. \[l\ne 0,\,\,m\ne 0,\,\,n\ne 0\] | |
| 1582. |
A unit vector in the \[xy-\]plane which is perpendicular to \[4\mathbf{i}-3\mathbf{j}+\mathbf{k}\] is [RPET 1991] |
| A. | \[\frac{\mathbf{i}+\mathbf{j}}{\sqrt{2}}\] |
| B. | \[\frac{1}{5}(3\mathbf{i}+4\mathbf{j})\] |
| C. | \[\frac{1}{5}\,(3\mathbf{i}-4\mathbf{j})\] |
| D. | None of these |
| Answer» C. \[\frac{1}{5}\,(3\mathbf{i}-4\mathbf{j})\] | |
| 1583. |
The vectors \[2\,\mathbf{i}+3\,\mathbf{j}-4\,\mathbf{k}\] and \[a\,\mathbf{i}+b\,\mathbf{j}+c\,\mathbf{k}\] are perpendicular, when [MNR 1982; MP PET 1988; MP PET 2002] |
| A. | \[a=2,\,\,b=3,\,\,c=-4\] |
| B. | \[a=4,\,\,b=4,\,\,c=5\] |
| C. | \[a=4,\,\,b=4,\,\,c=-\,5\] |
| D. | None of these |
| Answer» C. \[a=4,\,\,b=4,\,\,c=-\,5\] | |
| 1584. |
The vector \[2\,\mathbf{i}+\mathbf{j}-\mathbf{k}\] is perpendicular to \[\mathbf{i}-4\mathbf{j}+\lambda \mathbf{k},\] if \[\lambda =\] [MNR 1983; MP PET 1988] |
| A. | 0 |
| B. | ? 1 |
| C. | ? 2 |
| D. | ? 3 |
| Answer» D. ? 3 | |
| 1585. |
If \[\mathbf{a}=2\,\mathbf{i}+2\,\mathbf{j}+3\,\mathbf{k},\,\,\mathbf{b}=-\mathbf{i}+2\,\mathbf{j}+\mathbf{k}\] and \[c=3\,\mathbf{i}+\mathbf{j},\] then \[\mathbf{a}+t\,\mathbf{b}\] is perpendicular to c if \[t=\] [MNR 1979; MP PET 2002] |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» E. | |
| 1586. |
The vector \[2\,\mathbf{i}+a\,\mathbf{j}+\mathbf{k}\] is perpendicular to the vector \[2\,\mathbf{i}-\mathbf{j}-k,\] if \[a=\] [MP PET 1987] |
| A. | 5 |
| B. | ? 5 |
| C. | ? 3 |
| D. | 3 |
| Answer» E. | |
| 1587. |
A vector of length 3 perpendicular to each of the vectors \[3\,\mathbf{i}+\mathbf{j}-4\,\mathbf{k}\] and \[6\,\mathbf{i}+5\,\mathbf{j}-2\,\mathbf{k}\] is |
| A. | \[2\,\mathbf{i}-2\,\mathbf{j}+\mathbf{k}\] |
| B. | \[-\,2\,\mathbf{i}+2\,\mathbf{j}+\mathbf{k}\] |
| C. | \[2\,\mathbf{i}+2\,\mathbf{j}-\mathbf{k}\] |
| D. | None of these |
| Answer» B. \[-\,2\,\mathbf{i}+2\,\mathbf{j}+\mathbf{k}\] | |
| 1588. |
The angle between the vectors a + b and a ? b, when \[\mathbf{a}=(1,\,1,\,4)\] and \[b=(1,\,-1,\,4)\] is [Karnataka CET 2003] |
| A. | \[{{90}^{o}}\] |
| B. | \[{{45}^{o}}\] |
| C. | \[{{30}^{o}}\] |
| D. | \[{{15}^{o}}\] |
| Answer» B. \[{{45}^{o}}\] | |
| 1589. |
If a, b, c are mutually perpendicular unit vectors, then \[|\mathbf{a}+\mathbf{b}+\mathbf{c}|\,\,=\] [Karnataka CET 2002, 05; J & K 2005] |
| A. | \[\sqrt{3}\] |
| B. | 3 |
| C. | 1 |
| D. | 0 |
| Answer» B. 3 | |
| 1590. |
If \[\theta \] be the angle between the vectors \[12+m-2=0\] and \[\mathbf{b}=6\mathbf{i}-3\mathbf{j}+2\mathbf{k}\], then [MP PET 2001, 03] |
| A. | \[\cos \theta =\frac{4}{21}\] |
| B. | \[\cos \theta =\frac{3}{19}\] |
| C. | \[\cos \theta =\frac{2}{19}\] |
| D. | \[\cos \theta =\frac{5}{21}\] |
| Answer» B. \[\cos \theta =\frac{3}{19}\] | |
| 1591. |
The angle between the vector \[2i+3j+k\] and \[2i-j-k\] is [MNR 1990; UPSEAT 2000] |
| A. | \[\pi /2\] |
| B. | \[\pi /4\] |
| C. | \[\pi /3\] |
| D. | 0 |
| Answer» B. \[\pi /4\] | |
| 1592. |
If the sum of two unit vectors is a unit vector, then the magnitude of their difference is [Kurukshetra CEE 1996; RPET 1996] |
| A. | \[\sqrt{2}\] |
| B. | \[\sqrt{3}\] |
| C. | \[\frac{1}{\sqrt{3}}\] |
| D. | 1 |
| Answer» C. \[\frac{1}{\sqrt{3}}\] | |
| 1593. |
If three vectors a, b, c satisfy \[\mathbf{a}+\mathbf{b}+\mathbf{c}=\mathbf{0}\] and \[|\mathbf{a}|\,\,=\,\,3,\,\] \[|\mathbf{b}|\,=5,\] \[|\mathbf{c}|\,\,=7,\] then the angle between a and b is [Kurukshetra CEE 1998; UPSEAT 2001; AIEEE 2002; MP PET 2002] |
| A. | \[{{30}^{o}}\] |
| B. | \[{{45}^{o}}\] |
| C. | \[{{60}^{o}}\] |
| D. | \[{{90}^{\text{o}}}\] |
| Answer» D. \[{{90}^{\text{o}}}\] | |
| 1594. |
If the angle between two vectors \[\mathbf{i}+\mathbf{k}\] and \[\mathbf{i}-\mathbf{j}+a\mathbf{k}\] is \[\pi /3,\] then the value of \[a=\] [MP PET 1997] |
| A. | 2 |
| B. | 4 |
| C. | ? 2 |
| D. | 0 |
| Answer» E. | |
| 1595. |
The angle between the vectors \[(2\mathbf{i}+6\mathbf{j}+3\mathbf{k})\] and \[(12\mathbf{i}-4\mathbf{j}+3\mathbf{k})\] is [MP PET 1996] |
| A. | \[{{\cos }^{-1}}\left( \frac{1}{10} \right)\] |
| B. | \[{{\cos }^{-1}}\left( \frac{9}{11} \right)\] |
| C. | \[{{\cos }^{-1}}\left( \frac{9}{91} \right)\] |
| D. | \[{{\cos }^{-1}}\left( \frac{1}{9} \right)\] |
| Answer» D. \[{{\cos }^{-1}}\left( \frac{1}{9} \right)\] | |
| 1596. |
The value of x for which the angle between the vectors \[\mathbf{a}=-\,3\mathbf{i}+x\mathbf{j}+\mathbf{k}\] and \[\mathbf{b}=x\mathbf{i}+2x\mathbf{j}+\mathbf{k}\] is acute and the angle between b and x-axis lies between \[\pi /2\] and \[\pi \]satisfy [Kurukshetra CEE 1996] |
| A. | \[x>0\] |
| B. | \[x<0\] |
| C. | \[x>1\] only |
| D. | \[x<-1\] only |
| Answer» C. \[x>1\] only | |
| 1597. |
If \[\mathbf{a}=\mathbf{i}+2\mathbf{j}-3\mathbf{k}\] and \[\mathbf{b}=3\mathbf{i}-\mathbf{j}+2\mathbf{k},\] then the angle between the vectors \[\mathbf{a}+\mathbf{b}\] and \[\mathbf{a}-\mathbf{b}\] is [Karnataka CET 1994; Orissa JEE 2005] |
| A. | \[{{30}^{o}}\] |
| B. | \[{{60}^{o}}\] |
| C. | \[{{90}^{o}}\] |
| D. | x |
| Answer» D. x | |
| 1598. |
If q be the angle between two vectors a and b, then \[\mathbf{a}.\mathbf{b}\] \[\ge 0\] if [MP PET 1995] |
| A. | \[0\le \theta \le \pi \] |
| B. | \[\frac{\pi }{2}\le \theta \le \pi \] |
| C. | \[0\le \theta \le \frac{\pi }{2}\] |
| D. | None of these |
| Answer» D. None of these | |
| 1599. |
If a and b are unit vectors and \[\mathbf{a}-\mathbf{b}\] is also a unit vector, then the angle between a and b is [RPET 1991; MP PET 1995; Pb. CET 2001] |
| A. | \[\frac{\pi }{4}\] |
| B. | \[\frac{\pi }{3}\] |
| C. | \[\frac{\pi }{2}\] |
| D. | \[\frac{2\pi }{3}\] |
| Answer» C. \[\frac{\pi }{2}\] | |
| 1600. |
The position vector of vertices of a triangle ABC are \[4\mathbf{i}-2\mathbf{j},\,\mathbf{i}+4\mathbf{j}-3\mathbf{k}\] and \[-\mathbf{i}+5\mathbf{j}+\mathbf{k}\] respectively, then \[\angle ABC=\] [RPET 1988, 97] |
| A. | \[\pi /6\] |
| B. | \[\pi /4\] |
| C. | \[\pi /3\] |
| D. | \[\pi /2\] |
| Answer» E. | |