If cos α = 0.558 and sin β = 0.883 with both angles’ terminal rays in Quadrant-I, find the values of

Question

If    and with both angles’ terminal rays in Quadrant-I, find the values of 

(a)

cos(α+β)

(b)

sin(β−α)

Answer 1

1) determins cos β and sin α

2) use appropriate formula