 # Formulae: Can I Use an Area Formula?

In this worksheet, students must recognise when it is possible to use formulae for the area of the given shapes. Key stage:  KS 2

Curriculum topic:   Measurement

Curriculum subtopic:   Use Area/Volume Formulae

Difficulty level:   ### QUESTION 1 of 10

Use the following formulae to work out the areas of these shapes:

Rectangle We must know:

• the base length
• the perpendicular height from the base to the top.

Area of rectangle = base × height

Parallelogram We must know:

• the base length
• the perpendicular height from the base to the top. (NOT the slant height)

Area of parallelogram = base × height

Triangle We must know:

• the base length
• the perpendicular height from the base to the apex. (NOT the slant heights)

Area of triangle = ½ base × height

or

Area of triangle = base × height ÷ 2

Example 1

Can an area formula be used to work out the area of this parallelogram, and if so, which one? This is a parallelogram.

We must know:

• the base length
• the perpendicular height from the base to the top. (NOT the slant height)

We know the base length and the slant height, but not the perpendicular height.

No, we cannot use the area formula.

Example 2

Can an area formula be used to work out the area of this triangle, and if so, which one? This is a triangle.

We must know:

• the base length
• the perpendicular height from the base to the top. (NOT the slant height)

If we turn our heads to the left, the base length is 12 cm and the perpendicular height is 6 cm.

We do not need to know the slant height of 10 cm to use the formula.

Yes, we can use the area formula:

Area of triangle = ½ base × height

Which area formula can be used to work out the area of this rectangle? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this parallelogram? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this triangle? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this triangle? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this parallelogram? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this rectangle? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this square? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this triangle? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this rectangle? area = base × height

area = ½ base × height

neither of these

Which area formula can be used to work out the area of this right-angled triangle? area = base × height

area = ½ base × height

neither of these

• Question 1

Which area formula can be used to work out the area of this rectangle? area = base × height
EDDIE SAYS
This is a rectangle and we know the base length and the perpendicular height.
• Question 2

Which area formula can be used to work out the area of this parallelogram? area = base × height
EDDIE SAYS
This is a parallelogram and we know the base length and the perpendicular height.
• Question 3

Which area formula can be used to work out the area of this triangle? neither of these
EDDIE SAYS
This is a triangle.
We know the base length but not the perpendicular height.
• Question 4

Which area formula can be used to work out the area of this triangle? neither of these
EDDIE SAYS
This is a triangle.
None of the lengths given is the perpendicular height.
• Question 5

Which area formula can be used to work out the area of this parallelogram? area = base × height
EDDIE SAYS
This is a parallelogram.
The base is 55 mm and the perpendicular height is 26 mm.
• Question 6

Which area formula can be used to work out the area of this rectangle? neither of these
EDDIE SAYS
This is a rectangle.
We know the base length but not the perpendicular height.
• Question 7

Which area formula can be used to work out the area of this square? area = base × height
EDDIE SAYS
This is a square.
The base is 62 mm and the perpendicular height will be 62 mm too.
• Question 8

Which area formula can be used to work out the area of this triangle? area = ½ base × height
EDDIE SAYS
This is a triangle.
The base length is 14 cm and the perpendicular height is 5 cm.
• Question 9

Which area formula can be used to work out the area of this rectangle? neither of these
EDDIE SAYS
This is a rectangle.
The base length is 20 cm but the perpendicular height is not given.
• Question 10

Which area formula can be used to work out the area of this right-angled triangle? area = ½ base × height
EDDIE SAYS
This is a right-angled triangle.
The base length is 15 cm and the perpendicular height is 8 cm.
---- OR ----

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