Question 921956
RUle:
 SIn A *cos B + cos A*Sin B  = Sin( A+B)
 so sin 3π/5 x cos 7π/30 + cos 3π/5 x sin 7π/30 = sin(3π/5+7π/30)

we need to simply the expression in the brackets i.e 3π/5+7π/30
 multiply and divide with 30 
 
(3π/5) *(30/30)  + (7π/30)* (30/30)
 = (3π/1)*(6/30)+(7π/30)*(1/1)
 = 3*6π/30 +7π/30
  = 18π/30 +7π/30
 = (18π+7π)/30
   =25π/30
so sin( 25π/30) = {{{-1/sqrt(2)}}}