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

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