Question

What is the exact solution of cos 2x? Thank you!

Answer 1

119/169

Step-by-step explanation:

We use the following trig identity

`\cos2x=1-2\sin^2(x)`

Now in our case, we know that

`\sin x=-(5)/(13)`

therefore, our formula gives

`\cos2x=1-2*((5)/(13))^2`

which simplifies to give

`\boxed{\cos2x=(119)/(169).}`