How do you evaluate $4 cos^2(-pi/2)$ ?

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Answer 1 · 2016-08-04T09:47:07

As $cos(-\pi/2)=0$ , $4cos^2(-pi/2)=4(0^2)=0$ .

Remember that any multiple of $\pi$ plus or minus $\pi/2$ gives a cosine equal to zero.

Just a multiple of $\pi$ gives a sine equal to zero.

How do you evaluate 4 cos^2(-pi/2)4 cos^2(-pi/2)?