find the sine cosine and tangent of:

Quote:

Originally Posted by Yello

how do i find the sine cosine and tangent of:
pi/8.. pi/12... 4pi/3

I know this isn't that much related to calculus.. but its my first calculus assignment

Note that $\frac{\pi}{8}=\frac{1}{2}\left(\frac{\pi}{4}\right )$ and $\frac{\pi}{12}=\frac{1}{2}\left(\frac{\pi}{6}\righ t)$ . Then recall the following identities:

$\sin^2\left(\tfrac{x}{2}\right)=\frac{1-\cos x}{2}$

$\cos^2\left(\tfrac{x}{2}\right)=\frac{1+\cos x}{2}$

$\tan^2\left(\tfrac{x}{2}\right)=\frac{1-\cos x}{1+\cos x}$ .

You will need these to find sine, cosine and tangent at $\frac{\pi}{8}$ and $\frac{\pi}{12}$ .

To find sine, cosine, and tangent at $\frac{4\pi}{3}$ , you need to use the unit circle.

Can you take it from here?