Question

Q#1. If cos = -1/2 and 90 < x < 180, what is sin(x - 30)

Answer 1

Try this solution (this is not the only way!):

Q1: if cosx=-0.5 and x∈(90;180), it means x=120°.

So, sin(x-30)=sin(120-30)=sin90°=1.

answer: 1.

Q2: it tgx= -1/√3 and x∈(270°;360°), it means x=330°.

So, sin(x+30)=sin(330+30)=sin360°=0.

answer: 0.