Math CentralQuandaries & Queries


Question from Kevin, a student:

if the base of the triangle is 13ft and the altitude is 6ft then what is the area, and how do we calculate this?

Hi Kevin,

I drew a diagram of your triangle in orange and then enclosed it in a rectangle.


If you now draw a perpendicular line from the apex of the triangle to its base you have partitioned the rectangle into 4 triangles.


The two triangles on the left are congruent and the two on the right are congruent so the triangle you started with has half the area of the rectangle. The length of the rectangle is the length of the base of your triangle and the width of the triangle is the height of your triangle. The ares or a rectangle is the length times the width so

area of the triangle = 1/2 × base × height.

I hope this helps,

About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS