Question

Prove the following identity.
[sin(x+y)+sin(x-y)]/[cos(x+y)+cos(x-y)] = tan(x)

Answer 1

2 sin((x + y + x - y)/2)*cos((x + y -x +y)/2)
-------------------------------------------------
2cos((x + y + x- y)/2) *cos(x + y -x + y)



sinx
-------
cosx




tanx

Answer 2

sin(x+y)+sin(x-y)=2sinx cosy
cos (x+y)+cos (x-y)= 2 cos x cos y
when the first equation will be divided by the second one, 2 and cos y will be cancelled out..
u will get sinx/cosx=tanx

Answer 3

Hey arnab

Answer 4

hello

Answer 5

how are you, long time no see

Answer 6

i am fine. cleared kvpy first level. taking preparation for the interview.. :)

Answer 7

Cool KVPY I wish I had the opportunity

Good Luck! (Y)