How_To_Be_Good_At_Math

MEASUREMENT • WORKING OUT AREA WITH A FORMULA MEASUREMENT • WORKING OUT AREA WITH A FORMULA

Area and missing

measurements

Sometimes we know the length of

one side of a rectangle and its area,

but the length of the other side is

unknown. To find the missing length,

we simply need to use the numbers

that we know in a division calculation.

TRY IT OUT

Mystery length

Now you know how to

find a missing length,

see if you can do it

yourself. This rug has

an area of 6 m², and it

is 2 m wide. How long

is the rug?

This bedroom has an area

of 30 m², and we know

that it is 5 m wide. Let’s figure

out the length of the room.

To find the length, we

divide the area by the

width: 30 ÷ 5 = 6

This means that the room

has a length of 6 m.

To find a missing side length

when we know the area, we

just need to divide the area by

the side length we do know.

2 m

Area = 30 m²

Area = 6 m²

When you know the area of

a rectangle and the length

of one side, you can find the

length of the other side by

dividing the area by the

length you know.

?

WIDTH

5 m

LENGTH

?

Answer on page 319

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