Evaluate cos (pi - x)

We need to evaluate cos(∏-x)

Solution

We can evaluate cos(∏-x) using the trigonometric identity

cos (A – B) = cos A cos B + sin A cos B

Hence,

cos(∏-x)= cos π cos x + sin π sin x

Now will substitute the known values.

We know that cos π =-1 and sin π=0

Therefore

cos(∏-x)= (-1) cos x + sin π sin x

cos(∏-x)= -cosx + 0

cos(∏-x)= – cos X

Answer

cos(∏-x)= – cos x

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