Triangle Base Calculation: Finding BC When Area is 20 cm² and Height is 8

Question

The area of triangle ABC is 20 cm².

Its height (AD) is 8.

Calculate the length of the side BC.

00:00 Calculate BC

00:04 Examine the size of the sides and lines according to the given data

00:08 Apply the formula for calculating the area of a triangle

00:17 (height x base) divided by 2

00:22 Substitute in the relevant values and solve for BC

00:27 Multiply by the denominator to find BC

00:35 Isolate BC

01:03 This is the solution

We can insert the given data into the formula in order to calculate the area of the triangle:

$S=\frac{AD\times BC}{2}$

$20=\frac{8\times BC}{2}$

Cross multiplication:

$40=8BC$

Divide both sides by 8:

$\frac{40}{8}=\frac{8BC}{8}$

$BC=5$

5 cm