How do you derive the formula for a triangle?
1 Answer
Probably, the question is about a formula for an area of a triangle.
If not, ask more specifically.
Below is the proof of a formula
where
Explanation:
Consider triangle
An altitude
As seen from the picture, the area of each one of these right triangles is doubled, so the area of a rectangle with the same base
Since the area of a rectangle is
The drawing will be different in case of a triangle with an obtuse angle at the base. In this case an analogous transformation into a rectangle will represent our triangle not as a sum of two right triangles, but as their difference with the same final formula.