How do you prove sin(x+y)sin(x+y) = (tanx+tany)/(secxsecy)tanx+tanysecxsecy ?

1 Answer
Ananda Dasgupta
Jun 5, 2018

See below

Explanation:

sin(x+y) = sin x cos y+cos x sin ysin(x+y)=sinxcosy+cosxsiny
qquad = cos x cos y (sin x/cos x+sin y/cosy)
qquad = 1/sec x 1/sec y(tanx+tan y)
qquad = (tan x+tan y)/(sec x sec y)

Related questions
Impact of this question
2479 views around the world
You can reuse this answer
Creative Commons License