# Math Help - Trig Help - Unit Circle

1. ## Trig Help - Unit Circle

I need a little bit of explanation of how to do something.

for common angles you can find the cordinates and radians easily on charts, such as sin90 is (0,1) pi/2.
for angles like 15 and 75 degrees... how do i find thing. for any angle?

thnks

2. To find the sin of a nonstandard angle we need to use trig identities.

for example

$\sin(15)=\sin(45-30)$

using the difference identity we get...

$\sin(45-30)=\sin(45)\cos(30)-\sin(30)\cos(45)$

Now we could use the sin(15) to calculate the sin75 ect...

I hope this helps.