area of a triangle with vertices

hi,

i need to prove that the triangle with vertices (-2,8), (3,20) and (11,8) is isoceles. Find its area.

now for this question would i just need to draw it on a graph and dop;

BxH/2

13x12=156/2=78

if this is correct so far im unsure what to do after this point to find that it is isoceles.

help is required please!

thanks!

Re: area of a triangle with vertices

Quote:

Originally Posted by

**andyboy179** i need to prove that the triangle with vertices (-2,8), (3,20) and (11,8) is isoceles. Find its area.

You can find the length of each side.

The use the semi-perimeter rule to find the area.

Re: area of a triangle with vertices

i don't know what the semi-perimeter rule is.

Re: area of a triangle with vertices

Re: area of a triangle with vertices

hi, how do i use the distace formula on side AB?

Re: area of a triangle with vertices

sorry i know how to do it!!! mental block!! thanks alot for the answer!!!!