Question

if A=30° , then prove tan3A=3tanA-tan^3A/1-3 tan^3A

Answer 1

Put the value of A.

Tan 3A = 3 tan A - tan ^3 A / 1 - 3 tan ^2 A

1 - 3(tan 30)^2 = 1-3(1/root3)^2

=1-3*1/3

=1-1

=0

As the denominator is 0

The above term is ND which is same as tan 3*30 is tan 90