Finding the Height

Part of the Triangles section of Coddy's Geometry journey. Lesson 25 of 71.

When the area and the base are known, the formula becomes an equation for the height. For area 30 on a base of 10:

$A triangle with base 10 and an unknown dashed height h$

Area 30 and base 10, height unknown

30 = 1/2 × 10 × h

30 = 5h

h = 6

First work out half of the base: 1/2 × 10 = 5. That leaves a one-step equation, 30 = 5h, and dividing by 5 gives h = 6. Check the answer in the formula. A base of 10 and a height of 6 give 1/2 × 10 × 6 = 30, which matches the area.

Challenge

A triangle has area 48 and base 12.

$A triangle with base 12 and an unknown dashed height h$

Find its height h.

Try it yourself

48 = 1/2 * 12 * h

Solve for h

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

Finding the Height

All lessons in Triangles