Area of triangle base 3.5 height 4

Step by step

The question

Question: find the area of a triangle with base 3.5 and height 4.

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 3.5 long and 4 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 = 3.5 and h = 4.

Forget the points: 35 times 4 is 140.

The numbers have 1 digit after the point.

So the answer has 1 too: 14.0, which is 14.

That is the whole rectangle.

Half of 14 means 14 divided by 2.

That is 7.

So the area is 7 square units.

Let's look back.

First: half of a rectangle.

Last: use the rule.