# Thread: Centimeters to Radians for a Given Triangle?

1. ## Centimeters to Radians for a Given Triangle?

Greetings.

Given: I have a right triangle with sides of 5cm, 13cm, and sqrt(194)cm.

What is the equation to calculate the side of 5cm in radians? I'm pretty sure it involves atan, but am unsure how to implement it.

Thanks.

2. Originally Posted by sstecken
Greetings.

Given: I have a right triangle with sides of 5cm, 13cm, and sqrt(194)cm.

What is the equation to calculate the side of 5cm in radians? I'm pretty sure it involves atan, but am unsure how to implement it.

Thanks.

Angles are measured in radians...maybe they're asking for the angle opposite the 5cm length..then it would be the tan inverse of opposite/adjascent

3. Originally Posted by sstecken
Greetings.

Given: I have a right triangle with sides of 5cm, 13cm, and sqrt(194)cm.

What is the equation to calculate the side of 5cm in radians? I'm pretty sure it involves atan, but am unsure how to implement it.

Thanks.
As Las said, angles are measured in radians, not the length of a side. It is true that $5^2+ 13^2= 194$ so this is a right triangle. You can use any of the trig functions to answer this. Letting $\theta$ be the angle opposite the leg of length 5, we have
(1) $tan(\theta)= \frac{5}{13}$
(2) $cot(\theta)= \frac{13}{5}$
(3) $sin(\theta)= \frac{5}{\sqrt{94}}$
(4) $cos(\theta)= \frac{13}{\sqrt{94}}$
(5) $sec(\theta)= \frac{\sqrt{94}}{13}$
(6) $csc(\theta)= \frac{\sqrt{94}}{5}$

Use any one of those.

4. 1. Draw the triangle
2. It's a right triangle, so find the angle in degrees
3. Then convert the degrees to radians. 1 deg = 180/\pi radians

5. Why find the angle in degrees? Why not go directly to radians?