Posted by **Anonymous** on Monday, May 3, 2010 at 10:15am.

Find cos(s+t) if cos s= -1/2 and sin t= 3/5, s and t are in quadrant II.

I got the answer to be -4/10 plus -3sqrt(3)/10. Is that right?

Then a second problem was find sin (s+t) if sin s=2/3 and sin t=-1/3, sin is in quadrant II and t in quadrant IV. I got answer of 2sqrt(8/9) plus -sqrt(5)/9.

Can someone tell me if I did these right because I have a test tomorrow tahnks!

## Answer This Question

## Related Questions

- Precal - I do not understand how to do this problem ((sin^3 A + cos^3 A)/(sin A...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- trig - can someone please help me with this problem. i'm doing my review right ...
- Trig - Find sin(s+t) and (s-t) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are ...
- Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < ...
- Trig Help! - Question: Trying to find cos π/12, if cos π/6 = square ...
- MATH - Hi, I really need help with these questions. I did some of them halfway, ...
- trig - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...
- pre calc trig check my work please - sin x + cos x -------------- = ? sin x sin ...
- Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...

More Related Questions