# If A=[0 -tan(alpha)/2] tan(alpha)/2 0 ] and I is an identity matrix of order 2, then (I-A)[ cos(alpha) -sin(alpha) sin(alpha) cos(alpha)]is equal to?(A)A(B)I(C)I+A(D)none of the above

We prove that, $I+A=I-A\left[\begin{array}{cc}\mathrm{cos}\alpha & -\mathrm{sin}\alpha \\ \mathrm{sin}\alpha & \mathrm{cos}\alpha \end{array}\right]$

Hence, the correct option is C.

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