Question

If the area of a circle is 121π square units, what is its diameter?

If the circumference of a circle is 20π units, what is its area?

Answer 1

To find the diameter of a circle with a given area, use the formula d = 2√(A/π). For an area of 121π square units, the diameter would be 22 units. To find the area of a circle with a given circumference, use the formula A = (π/4)C². For a circumference of 20π units, the area would be 100π square units.

Step-by-step explanation:

To find the diameter of a circle with a given area, you can use the formula:

d = 2×√(A/π)

where d is the diameter and A is the area.

Using this formula, for an area of 121π square units, the diameter would be:

d = 2×√(121π/π) = 22 units

To find the area of a circle with a given circumference, you can use the formula:

A = (π/4)C²

where A is the area and C is the circumference.

Using this formula, for a circumference of 20π units, the area would be:

A = (π/4)(20π)² = 100π square units

Answer 2

area of a circle is defined as πr2 and the diameter as 2r. Plugin the value and you can solve problem c. As for problem d, circumference is 2πr, plugin the value and solve the equation.