Geometry - Circles

Front

What is the formula for the circumference of a circle?

Back

The circumference (C) of a circle is given by the formula: C = 2πr, where r is the radius.

Front

What is the formula for the area of a circle?

Back

The area (A) of a circle is given by the formula: A = πr², where r is the radius.

Front

How do you calculate the length of an arc in a circle?

Back

The length of an arc (L) can be calculated using the formula: L = (θ/360) * C, where θ is the angle in degrees and C is the circumference.

Front

What is a sector of a circle?

Back

A sector is a portion of a circle enclosed by two radii and the arc between them.

Front

How do you find the area of a sector?

Back

The area of a sector (A) can be calculated using the formula: A = (θ/360) * πr², where θ is the angle in degrees and r is the radius.

Front

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

Back

The diameter (d) of a circle is twice the radius: d = 2r.

Front

What is the value of π (pi)?

Back

π (pi) is approximately equal to 3.14 and is the ratio of the circumference of a circle to its diameter.

Front

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

Back

Using the area formula A = πr², the area is A = π(4)² = 16π cm².

Front

If a circle has a circumference of 20π cm, what is its radius?

Back

Using the circumference formula C = 2πr, the radius is r = C/(2π) = 20π/(2π) = 10 cm.

Front

What is the area of a circle with a diameter of 10 cm?

Back

First, find the radius: r = d/2 = 10/2 = 5 cm. Then, A = πr² = π(5)² = 25π cm².