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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