Area of a Triangle.

**kreshnik** · January 16th 2012, 10:42 AM

https://8842006143235788137-a-180274...attredirects=0

I don't know where to start. Some of my friends told me that I need an Angle!
Any advice?

**e^(i*pi)** · January 16th 2012, 10:53 AM

Originally Posted by kreshnik

https://8842006143235788137-a-180274...attredirects=0

I don't know where to start. Some of my friends told me that I need an Angle!
Any advice?

You can use the cos rule on triangle ABC to find angle B

$\cos(B) = \frac{|AB|^2+|BC|^2 - |AC|^2}{2|AB||BC|}$

**emakarov** · January 16th 2012, 11:10 AM

It's also possible to find the area of ABC using Heron's formula, and from there easily find the area of ACD.

Thread: Area of a Triangle.