IXL - Areas of similar figures (Geometry practice)

The figures below are similar.

2 ft

4 ft

What is the ratio of the area of the smaller circle to the area of the larger circle?

Write your answer as the ratio of two whole numbers separated by a colon (for example, 2:3).

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Learn with an example

question

The figures below are similar. The labeled sides are corresponding.

8 ft

4 ft

What is the ratio of the area of the larger rectangle to the area of the smaller rectangle?

Write your answer as the ratio of two whole numbers separated by a colon (for example, 2:3).

key idea

The following proportion applies to similar shapes:

where
a
b
is
the
ratio
of
the
corresponding
side
lengths,
and
A1
A2
is
the
ratio
of
the
areas.

solution

Find the square of the ratio of the corresponding side lengths.

Find the ratio of the areas.

Use these two ratios to set up a proportion.

Write the fraction as a ratio.

→

4:1

The ratio of the larger rectangle's area to the smaller rectangle's area is 4:1.

Looking for more? Try these:

Lesson: Similarity

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Teacher tools

Work it out

Not feeling ready yet? These can help:

M.6Perimeters of similar figures

S.2Area of rectangles and squares

S.3Area of parallelograms and triangles

S.4Area of trapezoids

Lesson: Similarity

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