Posted by **MW** on Monday, April 13, 2009 at 9:16pm.

In triangle ABC, b=14, c=15, and cos a= 3/5.

Find

a)side a

b) Sin B

Help please?

- Pre Calc -
**Reiny**, Monday, April 13, 2009 at 9:23pm
In this notation, small letters are usually used to represent sides, and capital letters to indicate the angles at the vertex,

so yours : b=14, c=15, cos A = 3/5

direct application of the cosine law

a^2 = 14^2 + 15^2 - 2(14)(15)cos A

= ....

once you have a

use the Sine Law to find angle B

- Pre Calc -
**MW**, Monday, April 13, 2009 at 9:53pm
ok. I have side A.

How do you find angle B?

- Pre Calc -
**Damon**, Monday, April 13, 2009 at 10:16pm
sin B/b = sin A/a

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