Question

Help with one more trig problem! Screenshot is attached

Answer 1

cos(a+b) = cosa.cosb - sina.sinb
sin(a+b) = sina.cosb + cosa.sinb
tan (a+b) = (tana+tanb) / (1-tana.tanb)

Answer 2

now let's check the signs of alpha and beta: alpha is in the third region where sin is and cos are both (-) and beta is in region 4 where sin is - and cos is +

Answer 3

Okay

Answer 4

sin a = -3/5, cos a = -4/5, sin b= -3/sqrt(13) and cos b = 2/sqt(13)

Answer 5

tan a = 3/4 and tan b = 3/2