If \[{{\cos }^{-1}}x-{{\cos }^{-1}}\frac{y}{2}=\alpha \] then \[4{{x}^{2}}-2xy\,\,\cos \alpha +{{y}^{2}}\] is equal to

If \[{{\cos }^{-1}}x-{{\cos }^{-1}}\frac{y}{2}=\alpha \] then \[4{{x}^

1.	If \[{{\cos }^{-1}}x-{{\cos }^{-1}}\frac{y}{2}=\alpha \] then \[4{{x}^{2}}-2xy\,\,\cos \alpha +{{y}^{2}}\] is equal to
A.	2 sin \[\alpha \]
B.	4
C.	\[4{{\sin }^{2}}\alpha \]
D.	\[-\,4{{\sin }^{2}}\alpha \]
Answer» D. \[-\,4{{\sin }^{2}}\alpha \]

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If \[{{\cos }^{-1}}x-{{\cos }^{-1}}\frac{y}{2}=\alpha \] then \[4{{x}^{2}}-2xy\,\,\cos \alpha +{{y}^{2}}\] is equal to

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