Question

Verify: cos(180° + x) = -cos x.

Answer 1

Yes, it does, You can also see this with cos(m + n) = (cos m)(cos n) - (sin m)(sin n)

Answer 2

cos(180 + x) = (cos 180)(cos x) - (sin 180)(sin x). Here the second term on the right is 0 times sin x

Answer 3

thanks! :)