Area of triangle base 9 height 7

Step by step

The question

Question: find the area of a triangle with base 9 and height 7.

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 9 long and 7 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 = 9 and h = 7.

9 times 7 is 63.

That is the whole rectangle.

Half of 63 means 63 divided by 2.

That is 31.5.

So the area is 31.5 square units.

Let's look back.

First: half of a rectangle.

Last: use the rule.