已知tan(a+b)=2/5,tan(b-π/4)=1/4,求tan(a+π/4)=?”

问题描述:

已知tan(a+b)=2/5,tan(b-π/4)=1/4,求tan(a+π/4)=?”

tan(a+π/4)=tan[(a+b)-(b-π/4)]
=[tan(a+b)-tan(b-π/4)]/[1+tan(a+b)·tan(b-π/4)]
=[2/5-1/4]/[1+(2/5)·(1/4)]
=3/22