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September 20, 2014

September 20, 2014

Posted by **Nan** on Friday, December 29, 2006 at 4:24pm.

cos u = 3/5; 0 < u < pi/2

cos v = 5/13; 3pi/2 < v < 2pi

Find:

sin (v + u)

cos (v - u)

tan (v + u)

First compute or list the cosine and sine of both u and v.

Then use the combination rules

sin (v + u) = sin u cos v + cos v sin u.

cos (v - u) = cos u cos v + sin u sin v

and

tan (u + v) = [tan u + tan v]/[1 - tan u tan v]

We got sin u = 4/5 & sin v = SQRT (7/13)

- Trig -
**qqq**, Saturday, November 29, 2008 at 7:54amif cos u=3/5

cos v=5/13

then sin u=4/5 and sin v=12/13

then sin(v+u)=sinv cos u+cos v sin u

sin(v+u)=56/65

cos(v-u)=63/65

Tan u=4/3 and tan v=12/5 then

tan(u+v)=-56/33

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