Question

solve the question in the attachment​

Answer 1

cos 40°+cos8p°+cos 160°=0

LHS=cos 40 +cos 80+cos 160

=0.766+0.173+(-0.939)

=0

=RHS

HOPE THIS HELPS YOU☺☺

Answer 2

we know that cos A+cosB=2(cos((A+B)/2)))((cos((A-B)/2))

so

cos80°+cos160°=2cos((80+160)/2)cos((80-160)/2)

= 2cos120°cos40°

now

cos80°+cos160°+cos40°=2cos120°cos40°+cos40°

=cos40°(2cos120+1)

=cos40(2×-1/2+1)

=cos40(-1+1)

=cos40(0)

=0

hope this helps you

please mark the answer as brainliest please

please FOLLOW me