# Math Help - find the exact value

1. ## find the exact value

cos(sin^-1 3/5) im not certain how to start solving this problem. any help would be appreciated. thanks

2. ## Re: find the exact value

Try a reference triangle. If you don't know what I mean, write back, I'll explain it more.

The basic idea is to draw a triangle with an angle of which the sine is 3/5. Then figure out what the cosine of that angle must be.

3. ## Re: find the exact value

thanks so much
so the ref triangle would tell me that the cos is 4/5? Its silly that was so easy. thanks again

4. ## Re: find the exact value

Yes. Keep that reference triangle in mind, it's often useful, in integration for example.