Question

已知tan α=2,求sin4α,cos4α,tan4α的值

Answer 1

tan2α=(2tanα)/(1-tan²α)= -4/3

由万能公式,

sin4α=(2tan2α)/(1+tan²2α)=-24/25

cos4α=(1-tan²2α)/(1+tan²2α)=-7/25

tan4α=(2tan2α)/(1-tan²2α)=24/7