Area of Circles

Front

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

Back

Area = π × r², where r is the radius.

Front

What does π (pi) represent in circle calculations?

Back

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

Front

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

Back

Area = π × (7)² = 3.14 × 49 = 153.86 cm².

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the radius. Diameter = 2 × radius.

Front

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

Back

Radius = Diameter ÷ 2.

Front

What is the area of a circle with a diameter of 10 cm?

Back

Area = π × (5)² = 3.14 × 25 = 78.5 cm².

Front

What is the radius of a circle with an area of 314 cm²?

Back

Radius = √(Area/π) = √(314/3.14) = 10 cm.

Front

If a circle has an area of 50.27 cm², what is its radius?

Back

Radius = √(50.27/π) ≈ 4 cm.

Front

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

Back

Area = π × (3)² = 3.14 × 9 = 28.26 cm².

Front

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

Back

Diameter = 2 × radius = 2 × 4 = 8 cm.