Question

Sin 20 degree×son 40 degree ×sin 60 degree×sin 80 degree=3 by 16

Answer 1

sin20 sin40 sin80 sin60

=1/4 sin60 sin 60
{sinx sin(60-x) sin(60+x)=1/4 sin 3x}
{ Put x=20}
=1/4 *(sin 60)2

=1/4 *3/4

=3/16

Solution for competitive exam