Question

If a= 30 degree verify that sin 3 a = 3 sin a - 4 sin cube a

Answer 1

LHS

= sin (3*30)

=sin90=1

RHS

=3sin30-4(sin30)^3
=3*1/2-4*(1/2)^3
=3/2-1/2
=1


so, LHS=RHS (proved)

Answer 2

if sinA=30,then we have to verify ,

3×1/2-4×1/2^3

=1