If sinA = 4/5 And

Given sinA = 4/5 And cosB = 5/13

We know that where 0 <A,B < π/2

Then,

(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

(iii) Sin(A –B)

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

(iv) Cos(A –B)

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