What is the exact value of cosθ in simplified form?
cos θ = - √ [ 1 - sin^2 θ ] =
- √ [ 1 - (4/7)^2 ] =
- √ [ 1 - 16/ 49 ] =
- √ [ 49 - 16] / 7 =
- √33 / 7
We take the negative root because the cosine i negative in quadrant 2
