# Thread: How to calculate perimeter of a triangle, tricky one?

1. ## How to calculate perimeter of a triangle, tricky one?

Hello, I would like to ask a question which I can't figure out by myself, I'll skip chatter and shoot it:

I need to calculate the length of the perimeter of the circle, but I don't know how I can do that when no lengths at all have been given, so please advise.
This is how I progressed: Aijaa.com - 5598188.jpg

Oh, and I have a 9 hour deadline on this, starting now :X

2. Your problem can't be solved in terms of numercial lengths as you only have an angle to begin with.

3. Oh god I missed something, also the radius of the circle was given (r=12cm) :l Shouldn't do these things when I'm tired, but what did we learn? Read the description!

4. Originally Posted by mazzuli
I need to calculate the length of the perimeter of the circle,
Also known as the circumference you have the formula

$\displaystyle C = 2\pi r$

Originally Posted by mazzuli
also the radius of the circle was given (r=12cm)
$\displaystyle C = 2\pi r$
$\displaystyle C = 2\times \pi \times 12$