Posted by **chris** on Thursday, November 18, 2010 at 10:33pm.

find exact value cos(13pi/15)cos(-pi/5)-sin(13pi/15)sin(-pi/5)

## Answer This Question

## Related Questions

- Math - 3. find the four angles that define the fourth root of z1=1+ sqrt3*i z = ...
- Trigonometry - If cos(a)=1/2 and sin(b)=2/3, find sin(a+b), if 1) Both angles ...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- Precalculus/Trig 6 - Find the exact value of the following trigonometric ...
- Homework Help Calculus - Find the linear approximation L(x)of the function f(x)=...
- trig - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...
- tigonometry - expres the following as sums and differences of sines or cosines ...
- Math - Given that cos 13pi/18=sin y, first express 13pi/18 as a sum of pi/2 and ...
- Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...
- Trig - Find sin(s+t) and (s-t) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are ...

More Related Questions