1.

If $$x\cos \theta- y\sin \theta $$= $$\sqrt {{x^2} + {y^2}} $$and $$\frac{{{{\cos }^2}\theta }}{{{a^2}}}$$+ $$\frac{{{{\sin }^2}\theta }}{{{b^2}}}$$= $$\frac{1}{{{x^2} + {y^2}}}{\text{,}}$$then the correct relation is?

A. $\frac{{{x^2}}}{{{b^2}}} - \frac{{{y^2}}}{{{a^2}}} = 1$$
B. $\frac{{{x^2}}}{{{a^2}}} + \frac{{{y^2}}}{{{b^2}}} = 1$$
C. $\frac{{{x^2}}}{{{b^2}}} + \frac{{{y^2}}}{{{a^2}}} = 1$$
D. $\frac{{{x^2}}}{{{a^2}}} - \frac{{{y^2}}}{{{b^2}}} = 1$$
Answer» C. $\frac{{{x^2}}}{{{b^2}}} + \frac{{{y^2}}}{{{a^2}}} = 1$$


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