Question

Question #e44f8

Answer 1

`\cos(2\theta)=7/25=0.28`

Explanation:

We have the double-angle formulas:

`\cos(2\theta)=2\cos^2(\theta)-1`
`=\cos^2(\theta)-\sin^2(\theta)`
`=1-2\sin^2(\theta)`

With \sin(\theta)=3/5 given we use the last of these expression to get:

`\cos(2\theta)=1-2\times(3/5)^2`
`=7/25`