How_To_Be_Good_At_Math

MEASUREMENT • AREAS OF TRIANGLES MEASUREMENT • AREAS OF PARALLELOGRAMS 173

Areas of

parallelograms

Parallelograms aren’t too different from rectangles – they're

quadrilaterals with opposite sides that are parallel and equal

in length. Because parallelograms are so like rectangles, we

can use the same formula to work out their areas.

First, let's draw a line straight down

from the top corner of the

parallelogram to its base. It creates a

right-angled triangle.

Imagine you could chop this triangle

off and carry it over to the other end

of the parallelogram.

When you stick the triangle on the

other end, it fits perfectly and makes

the parallelogram into a rectangle.

This means that we can find the area by

multiplying the height of the parallelogram

by the length of the base, just like we did with

the rectangle:

Area of a parallelogram = base x height

Look at this parallelogram. Let’s see

why its area formula is the same as

that of a rectangle.

Draw a straight

line to make a

triangle

Moving the

triangle turns the

parallelogram into

a rectangle

The area of a

parallelogram is:

base × height

HEIGHT

BASE

172_173_Areas_of_triangles_and_parallelograms.indd 173 29/02/2016 18:03