Circles

Front

What is the diameter of a circle?

Back

The diameter is a line that goes from one end of the circle to the other and crosses the center point.

Front

What is the formula for the area of a circle?

Back

A = π × r², where r is the radius.

Front

If a circle has a radius of 4 cm, what is its area?

Back

The area is 50.24 cm².

Front

What is the radius of a circle if the diameter is 12 cm?

Back

The radius is 6 cm.

Front

What is the area of a semicircle with a diameter of 8 cm?

Back

The area is 25.12 cm².

Front

Define the term 'radius' in relation to a circle.

Back

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

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the length of the radius (D = 2r).

Front

How do you calculate the circumference of a circle?

Back

The circumference can be calculated using the formula C = π × D or C = 2π × r.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

If the radius of a circle is doubled, how does the area change?

Back

The area increases by a factor of four.