Find the exact value of the following under the given conditions a.cos(a-b) b.(a-b) c.tan(a-b)

Question

sin b=-9/23,pi<β<3pi/2

cos a=-35/37, pi/2<β<pi

Answer 1

I don't know how to interpret: sin b=-9/23,pi<β<3pi/2cos a=-35/37, pi/2<β<pi

is ß < 3pi or 3pi/2 or 3pi/2 ???