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
