Circles

Front

What is a circle?

Back

A circle is a shape consisting of all points in a plane that are at a given distance from a fixed point, called the center.

Front

What is the radius of a circle?

Back

The radius is the distance from the center of the circle to any point on its circumference.

Front

What is the diameter of a circle?

Back

The diameter is the distance across the circle through the center, equal to twice the radius.

Front

How do you calculate the area of a circle?

Back

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

Front

What is the circumference of a circle?

Back

The circumference is the distance around the circle, calculated using the formula C = 2πr or C = πd, where d is the diameter.

Front

If the radius of a circle is 5 cm, what is the area?

Back

A = π(5 cm)² = 78.54 cm² (approximately 78.27 cm²).

Front

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

Back

The radius is half of the diameter, so the radius is 5 cm.

Front

What is the relationship between radius and diameter?

Back

The diameter is always twice the length of the radius.

Front

What is π (pi)?

Back

π (pi) is a mathematical constant approximately equal to 3.14, representing the ratio of the circumference of a circle to its diameter.

Front

If a circle has an area of 50.27 cm², what is the radius?

Back

Using the area formula A = πr², the radius can be calculated as r = √(A/π) = √(50.27/π) ≈ 4.01 cm.