Question

Can someone please also assist with this problem for some reason I cant wrap my head around this.
Given: 5 sin α = 3 & tan β = -1, where α,β ∈ (90°; 270°). Determine the value of the below without a calculator.
1.1. cos α

1.2. sin 2β

please show how you did 1.1 & 1.2

Answer 1

U can apply identity in 2nd part easily which is Sin2theta=2sin theta cos theta

Hope it helps u^_^....