Area & Circumference of A Circle

Front

What does r represent in the formula A = π·r²?

Back

r represents the radius of the circle.

Front

What number does π represent?

Back

π represents approximately 3.14.

Front

What is the formula to calculate the area of a circle?

Back

A = π·r².

Front

What does A represent in the formula A = π·r²?

Back

A represents the area of the circle.

Front

What is the formula to calculate the circumference of a circle?

Back

C = 2·π·r or C = π·d.

Front

If the radius of a circle is 10 cm, what is the area?

Back

A = π·(10)² = 314 cm².

Front

If the diameter of a circle is 20 cm, what is the radius?

Back

The radius is 10 cm.

Front

What is the circumference of a circle with a radius of 8 cm?

Back

C = 2·π·8 = 50.24 cm.

Front

What is the relationship between diameter and radius?

Back

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

Front

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

Back

r = √(A/π) = √(78.5/3.14) ≈ 5 cm.