# Thread: find the sine cosine and tangent of:

1. ## find the sine cosine and tangent of:

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

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

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

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

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

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

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

Can you take it from here?