How do you use the area of a triangle to solve for b?
Just to confirm, what you mean "b" is base, right?
If so, then the equation for solving the area for the triangle is
On this website:
It explains that a rectangle is composed of 2 triangles.
Just to refresh your mind,
Now to the next part, where you asked of how to apply it on finding the base, if the question didn't prove a number of the base for you, you just do the same thing.
Since I'm bad at explaining, I'm going to give you 2 examples so you will understand:
Ex. 1: A triangle has an area of 16 cm and a height of 4 cm. How long is the base?
Area (triangle) =
Hope this helps!!