If SinA = 12/13 And sinB = 4/5, where π/2

Question

If SinA = 12/13 And sinB = 4/5, where π/2<A < π And 0 <B < π/2, find the following: (i) sin(A +B) (ii) cos(A +B)

Philoid · Accepted Answer

Given sinA = 12/13 And sinB = 4/5 where π/2

We know that

(i) Sin(A +B)

We know that sin(A +B) = sinA cosB + cosA sinB

(ii) Cos(A +B)

We know that cos(A +B) = cosA cosB - sinA sinB