Exploring Circle Area and Circumference

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

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

Back

If the radius is doubled, the area increases by a factor of four (4).

Front

What is the relationship between diameter and radius?

Back

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

Front

How do you find the radius if you know the diameter?

Back

To find the radius, divide the diameter by 2: r = d/2.

Front

What is the circumference of a circle with a radius of 5 cm?

Back

C = 2π(5) = 10π cm.

Front

What is the area of a circle with a radius of 3 inches?

Back

A = π(3)² = 9π in².

Front

If a circle has a circumference of 31.4 cm, what is its radius?

Back

Using C = 2πr, the radius r = C/(2π) = 31.4/(2π) = 5 cm.

Front

What is the diameter of a circle with a circumference of 20π meters?

Back

Using C = πd, the diameter d = C/π = 20π/π = 20 m.

Front

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

Back

A = π(4)² = 16π cm².