IXL | Area between two triangles

What is the area of the shaded region?

13 ft

14 ft

9 ft

10 ft

Write your answer as a whole number or a decimal rounded to the nearest hundredth.

square feet

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Learn with an example

question

What is the area of the shaded region?

20 ft

13 ft

12 ft

7 ft

Write your answer as a whole number or a decimal rounded to the nearest hundredth.

square feet

key idea

To find the area of a figure with a hole in it, subtract the area of the inner shape from the area of the outer shape.

Area of a triangle:

area

base

height

solution

To find the area of the shaded region, subtract the area of the inner shape from the area of the outer shape. Start by finding the area of the inner shape.

Find the base and height of the inner triangle.

base: 12 ft

height: 7 ft

Use these numbers in the formula.

inner area

base

height

Now find the units. The lengths are measured in feet, so the area is measured in square feet.

The area of the inner triangle is 42 square feet.

Next, find the area of the outer shape.

Find the base and height of the outer triangle.

base: 20 ft

height: 13 ft

Use these numbers in the formula.

outer area

base

height

130

As with the inner triangle, the lengths of the outer triangle are measured in feet. So, the area is measured in square feet.

The area of the outer triangle is 130 square feet.

Finally, subtract the inner area from the outer area to find the area of the shaded region.

shaded area

130

–

The area of the shaded region is 88 square feet.

Looking for more? Try these:

Lesson: Area of triangles

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Teacher tools

Work it out

Not feeling ready yet? These can help:

GG.6Area of triangles

H.6Subtract numbers up to three digits

Lesson: Area of triangles

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