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.	4
B.	\[2{{\sin }^{2}}\alpha \]
C.	\[-4{{\sin }^{2}}\alpha \]
D.	\[4{{\sin }^{2}}\alpha \]
Answer» E.

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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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