Area and Circumference of a Circle

Front

What is the formula for the area of a circle?

Back

A = πr², where A is the area and r is the radius.

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the radius: d = 2r.

Front

How do you calculate the circumference of a circle using diameter?

Back

C = πd, where C is the circumference and d is the diameter.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

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

Back

A = π(5)² = 78.5 cm² (approximately 79 cm² when rounded).

Front

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

Back

C = πd = π(10) ≈ 31.4 cm.

Front

What is the circumference of a circle with a radius of 7 cm?

Back

C = 2πr = 2π(7) ≈ 43.96 cm (approximately 44 cm when rounded).

Front

What is the diameter of a circle with a radius of 3.5 cm?

Back

d = 2r = 2(3.5) = 7 cm.

Front

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

Back

A = πr² = π(4)² = 50.24 cm² (approximately 50 cm² when rounded).

Front

Can a triangle have sides of lengths 3, 8, and 9?

Back

Yes, it satisfies the triangle inequality theorem.