Question

Выразите tg 4a через tg a

Answer 1

tg4a=2tg2a/(1-tg²2a)=(4tga/(1-tg²a)):(1-4tg²a/(1-tg²a)²)=(4tga/(1-tg²a))•((1-tg²a)²/((1-tg²a)²-4tg²a)))=
(4tga-4tg³a)/(tg⁴a-6tg²a+1)