Question

已知tan(a-兀/4)=3，求tana

Answer 1

tan(a-π/4)=3
(tana-tanπ/4)/(1+tanatanπ/4) = 3
(tana-1)/(1+tana) = 3
tana-1=3+3tana
2tana=-4
tana=-2

Answer 2

tana=tan[a-π/4)-π/4]
=[tan(a-π/4)-tanπ/4]/[1+tan(a-π/4)tanπ/4]
=(3-1)/(1+1*3)
=1/2