Area of a Circle

Front

What is the formula for the area of a circle?

Back

The area of a circle is calculated using the formula A = πr², where A is the area and r is the radius.

Front

How do you find the radius if you know the diameter of a circle?

Back

The radius is half of the diameter. If the diameter is d, then the radius r = d/2.

Front

What is the value of π (pi) to two decimal places?

Back

π (pi) is approximately 3.14.

Front

If the radius of a circle is 10 cm, what is its area?

Back

Using the formula A = πr², the area is A = π(10)² = 314.16 cm².

Front

What is the relationship between diameter and radius in a circle?

Back

The diameter is twice the length of the radius. If r is the radius, then d = 2r.

Front

How do you convert the area from square centimeters to square meters?

Back

To convert from square centimeters to square meters, divide the area in cm² by 10,000.

Front

What is the area of a circle with a radius of 5 inches?

Back

Using the formula A = πr², the area is A = π(5)² = 78.54 in².

Front

If the area of a circle is 50 cm², what is the radius?

Back

To find the radius, use the formula r = √(A/π). So, r = √(50/π) ≈ 3.99 cm.

Front

What is the diameter of a circle with an area of 78.5 cm²?

Back

First, find the radius using r = √(A/π). Then, the diameter d = 2r. For A = 78.5 cm², d ≈ 10 cm.

Front

What is the area of a circle with a diameter of 20 meters?

Back

First, find the radius: r = 20/2 = 10 meters. Then, A = π(10)² = 314.16 m².