Question

Prove sin(x+y)=sin(x)cos(y) + cos(x)sin(y), use the left side to start and use the trig identities as in the proof. How do I do this?

Answer 1

From the identity sin (A+b) = sinAcosB + cosAsinB
We can prove that:
sin(x+y) = sin(x)cos(y)+cos(x)sin(y)
Hence
sin(x)cos(y)+cos(x)sin(y) = sin(x)cos(y)+cos(x)sin(y)
That's it. :)

Answer 2

if you're looking for derivation of sin(x+y) :-
https://www.khanacademy.org/math/trigonometry/less-basic-trigonometry/trig_iden_tutorial/v/proof--sin-a-b------cos-a--sin-b-----sin-a--cos-b

Answer 3

wow now that i look at it it seems so obvious haha thank you!