Area of Circles

Front

What is the formula for finding the area of a circle?

Back

A = π·r²

Front

If you are given the diameter, how can you calculate the radius?

Back

Divide the diameter by 2

Front

What is the distance across a circle through its center called?

Back

Diameter

Front

What is the radius of a circle?

Back

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

Front

What is π (pi)?

Back

A mathematical constant approximately equal to 3.14, representing the ratio of a circle's circumference to its diameter.

Front

How do you calculate the circumference of a circle?

Back

C = 2·π·r or C = π·d

Front

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

Back

A = π·(7)² = 154 cm² (approximately)

Front

What happens to the area of a circle if the radius is doubled?

Back

The area increases by a factor of four.

Front

If the area of a circle is 78.5 cm², what is the radius?

Back

r = √(A/π) = √(78.5/π) ≈ 5 cm

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the radius (d = 2·r).