Question

prove that tan 70 degree equal to tan 20 degree + 2 tan 50 degree​

Answer 1

tan (70) = tan (50+20)
= tan 50 + tan 20/1-tan 20tan 50
So,
tan 70 - tan 70*tan 50*tan 20 = tan 50 + tan 20
tan 70 - cot 20 tan 20 tan 50 = tan 50 + tan 20
So
tan 70 - tan 50 = tan 50 + tan 20
Therefore,
tan 70 = 2 tan 50 + tan 20

Hence proved

Answer 2

As we all know,
According to the trigonometric
Identity,
tan 70= tan (20+50)
tan 70= (tan 20+tan 50)/1- tan 20 tan 50
tan 70- tan 20 tan 50 tan 70
Also,tan 70 tan 20
= tan 70 cot 70
=1
Hence,
tan 70-tan 50
So tan 70= tan 20+2 tan 50
Hope this helps u :) :)