Circumference and Area of a Circle

Front

What is the formula for the circumference of a circle?

Back

C = π·d, where C is the circumference and d is the diameter.

Front

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

Back

The radius is half of the diameter. (r = d/2)

Front

If the radius of a circle is 7 cm, what is the diameter?

Back

The diameter is 14 cm.

Front

What is the area of a circle with a radius of 4 cm?

Back

Area = π·r² = π·(4)² = 16π cm² (approximately 50.24 cm²).

Front

What does the symbol π (pi) represent?

Back

π is a constant approximately equal to 3.14, representing the ratio of the circumference of a circle to its diameter.

Front

How do you calculate the area of a circle?

Back

Area = π·r², where r is the radius.

Front

What is the circumference of a circle with a diameter of 10 m?

Back

Circumference = π·d = π·10 m (approximately 31.4 m).

Front

If the circumference of a circle is 31.4 cm, what is the diameter?

Back

Diameter = C/π = 31.4 cm/π (approximately 10 cm).

Front

What is the area of a circle with a diameter of 12 cm?

Back

Area = π·(r)² = π·(6)² = 36π cm² (approximately 113.1 cm²).

Front

What is the diameter of a circle if the area is 78.5 cm²?

Back

Diameter = 2√(Area/π) = 2√(78.5/π) (approximately 10 cm).