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

## Answer this Question

## Related Questions

- maths - Choose three options which are true: a) an angle of 150 degrees is ...
- Pre-Calc - Consider a triangle ABC. C is a right angle, and side a is opposite ...
- maths - Choose three options which are true: a) an angle of 150 degrees is ...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- Geometry Please Help With One Multiple Choice - Write the ratios for sin A and ...
- Math - Calculus - The identity below is significant because it relates 3 ...
- pre calc trig check my work please - sin x + cos x -------------- = ? sin x sin ...
- Trigonometry - in triangle abc, if sin c= (sin a + sin b )/ ( cos a + cos b ) ...
- Geometry One multiple choice question! - Write the ratios for sin A and cos A. {...
- Math sin/cos - On a piece of paper draw and label a right triangle using the ...