Question

Show that sin 80 = 8 sin 0 cos O cos 20 cos 40​

Answer 1

Answer:

L. H. S = sin 8 Φ

= sin ( 4Φ + 4Φ)

= 2 sin 4Φ cos 4Φ

=2.2 sin2 Φ cos 2Φ cos 4Φ

=4.2 sin Φ cos Φ cos 2Φ cos 4Φ

R. H. S =8 sin Φ cos Φ cos 2Φ cos 4Φ

hence proved

hope it helps