1. Mar 22, 2013

### k_poorahong

1. The problem statement, all variables and given/known data

If we know θ3, A, B, C, How can we find these 2 angle (θ1 and θ2). Please help me find the equation.

2. Relevant equations

Credit : http://www.mathsisfun.com/algebra/trig-sine-law.html
The Law of Sines (or Sine Rule) is very useful for solving triangles:

It works for any triangle:

a, b and c are sides.

A, B and C are angles.

(Side a faces angle A,
side b faces angle B and
side c faces angle C).

a/sin A = b/sin B = c/sin C

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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2. Mar 22, 2013

### Simon Bridge

Welcome to PF;
You are on to a good start with the law of sines and the law of cosines.
Did you try applying them?

It may help to arm yourself with a list of trig identities too.
Note: you may have to use the unlabelled lengths and angles as intermediate steps.
Don't be frightened to experiment.
For instance - if θ1=θ3, then What is the relationship between B and C?
In this case they are not equal though - what is the relationship?

Last edited: Mar 22, 2013