dont know which side is base or height

I have a triangle located at the points A(-2,5),B(1,3),C(-1,0)

The distance from point A to B is $\displaystyle \sqrt{13}$.

The distance from point B to C is $\displaystyle \sqrt{13}$

The distance from point A to C is $\displaystyle \sqrt{26}$

The book wants me to find the area of the triangle. But I dont even know what the base or the height of the triangle is. How do I know what the base is and what the height is?

Edit: I think I may have just figured something out. Are the sides adjacent to the right angle always the base and height? Yeah that seems so obvious now.

But what about triangles that arent right triangles? How would I go about finding the base and height of those?