Question

Verify each identity:
(tanx+tany)/(1-tanxtany)=(sinxcosy+cosxsiny)/(cosxcosy-sinxsiny),

Answer 1

Solution:
(tanx + tany)/(1-tanxtany) is equal to the formula of tan(x+y)
sinxcosy + cosxsiny = is equal to the formula of sin(x+y)formula
cosxcosy - sinxsiny) = is equal to the formula of cos(x+y)

So this means that
tan(x+y) = sin(x+y)/cos(x+y)