(1+tgx)/(1-tgx)=tg(п/4+x)

Question

(1+tgx)/(1-tgx)=tg(п/4+x)

Answer 1

Tg(π/4+x)=(tgπ/4+tgx)/(1-tgπ/4*tgx)=(1+tgx)/(1-tgx)