Question

Simplify for 2 points cosx + cos(180º -x)

Answer 1

cos x+ cos(180-x)
=cos x + (cos 180)(cosx) +sin(180)(sinx))
=cos x+{-1(cos x)+0(sinx)
Note cos 18
`0^(o)`=-1 sin 18
`0^(o)`
= cos x-cos x
=0