# Trig/geometry help (triangles/finding sides)

1. Dec 17, 2012

### PhizKid

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

Find side 'R'. L = 6.10 meters, theta = 36.9 degrees, and phi = 53.1 degrees.

2. Relevant equations
Pythagorean Theorem
Similar triangles
Law of Sines
Law of Cosines

3. The attempt at a solution
I don't see any way I can attempt this, I'm very rusty with my trig. We have a known side and a right angle, but I don't see how I can make any other angles (since we only have one side I'm assuming I need to get an angle somewhere

2. Dec 17, 2012

### Mentallic

Draw a vertical line through the right side of the length L (the point on the triangle). The length L will be perpendicular to this line, yes? And now take notice that $\phi$ would be the angle between the vertical and the side of the triangle because of the parallel lines rule (the wall is parallel to the vertical line we constructed).

3. Dec 17, 2012

### lurflurf

law of sines gives

L/sin(phi+theta)=R/cos(phi)