Question

sinθ=-9/10, θ is in quad IV, find sin and cos of 2θ

Answer 1

why do you post it twice?

Answer 2

i didn't mean to

Answer 3

\(cos 2\theta = 1-2sin^2 \theta\) just plug the number in to get cos \(2\theta\)

Answer 4

about sin \(2\theta\) there are 2 easiest way to figure out,
1/ algebraic way
2/geometric way
pick one

Answer 5

However, I guide you only, I don't work for you and I don't force you study. If you don't want to study, it's FINE to me

Answer 6

I am working on it. . .