Question

if sin b =4/5 and b lies in 1st quadrant find the value of sin (a+b)

Answer 1

Answer:

sinA=45

cosA=1−1625−−−−−√=35

cosB=−1213

sinB=−513(ln3sinθ/9ud)

cos(A+B)2

cosAcosB−sinAsinB

35×−1213−45×−513

−36+205×13=−1665