# Help finding sides with other angles of other triangles nearby

• December 17th 2012, 01:56 AM
PhizKid
Help finding sides with other angles of other triangles nearby
http://i.imgur.com/h83RV.png
I have to find side 'R'
L = 6.10 meters, theta = 36.9 degrees, and phi = 53.1 degrees.

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
• December 17th 2012, 10:10 AM
earboth
Re: Help finding sides with other angles of other triangles nearby
Quote:

Originally Posted by PhizKid
http://i.imgur.com/h83RV.png
I have to find side 'R'
L = 6.10 meters, theta = 36.9 degrees, and phi = 53.1 degrees.

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

1. I've modified your sketch a little bit (see attachment

2. According to the definition of the Sine function in a right triangle you'll get:

$\frac RL = \sin(90^\circ - \theta)$

3. Since L and $\theta$ are known you can determine R.
• December 18th 2012, 03:25 AM
earboth
Re: Help finding sides with other angles of other triangles nearby
$\frac RL = \sin(90^\circ - \theta)$

Sorry but this line should read:

$\frac RL = \sin(90^\circ - \phi)$