Finding the radius of a circle circumscribed around a square

In this publication, we will consider formulas with which you can calculate the radius of a circle circumscribed about a square. We will also analyze examples of solving problems to consolidate the material presented.

Content

Formulas for calculating the radius of the circumscribed circle

Finding the radius of a circle circumscribed around a square

Through the side of the square

Radius R the circumscribed circle of a square is equal to the length of its side atimes the square root of two and divided by two.

Finding the radius of a circle circumscribed around a square

Through the diagonal of the square

Radius R circumscribed around the square of a circle is equal to half of its diagonal d.

Finding the radius of a circle circumscribed around a square

Examples of tasks

Task 1

The length of the side of the square is 8 cm. Find the radius of the circle circumscribed around it.

Solution

Let’s apply the first formula discussed above:

Finding the radius of a circle circumscribed around a square

Task 2

Calculate the length of the diagonal of a square if the radius of the circumscribed circle is 6 cm.

Solution

As we know, the radius of the circumscribed circle is equal to half the diagonal of the square. Therefore, the total length of the diagonal is 12 cm (6 cm ⋅ 2).

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