Question

cos40+cos80+cos160=
ansr plzz

Answer 1

cos40+ cos 80+ cos160
0.76 + 0.17 -0.97
-0.04

Answer 2

Answer:

cos40+cos80+cos160=0

=cos40+(cos80+cos160)

=cos40(2cos(80+160/2)cos(80-160/2))

=cos40+2cos(240/2)cos(-80/2)

=cos40+2cos(180-60)-cos 40

=cos40+(-2cos60+cos40)

=cos40(1-2(1/2)

=cos40(1-1)

=cos40(0)

=0