Question

If sin x=3/5 cos y=-12/13

where
π/2<x< π and
π/2<y<π
Prove that, sin(x + y)= -56/65​

Answer 1

Step-by-step explanation:

Sin(x+y)= -56/65

L.H.S.

By[Sin(x+y)=Sinx*Cosy+Cosx*Siny]

=> 3/5*(-12/13)+Cosx*Siny

[By golden triangles of 3,4,5 and 5,12,13]

=>Cosx= -4/5

=>Siny= 5/13

=> -36/65+(-4/5)*5/13

=> -36/65 - 20/65

=> -56/65

As, L.H.S. = R.H.S.

Hence Proved

Answer 2

Answer:

$\huge\mathfrak{Answer\:is\:56/65}$

refer to the attachment