Area of triangle base 8 cm height 5 cm

Step by step

The question

Question: find the area of a triangle with base 8 cm and height 5 cm.

1 Half of a rectangle

The height goes straight up from the base to the top corner.

It makes a right angle with the base.

Draw a box around the triangle: a rectangle 8 cm long and 5 cm high.

The triangle fills exactly half of the box.

2 Use the rule

So the area is half of base times height: A = ½ × b × h.

Now put the numbers in: b = 8 and h = 5.

8 times 5 is 40.

That is the whole rectangle.

Half of 40 means 40 divided by 2.

That is 20.

So the area is 20 cm².

Let's look back.

First: half of a rectangle.

Last: use the rule.