Area 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

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

Back

A = π(7)² = 153.94 cm².

Front

What does π (pi) represent in the context of circles?

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 radius if you know the area of a circle?

Back

r = √(A/π), where A is the area.

Front

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

Back

A = π(5)² = 78.54 cm².

Front

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

Back

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

Front

If the area of a circle is 50.24 cm², what is the radius?

Back

r = √(50.24/π) ≈ 4 cm.

Front

What is the area of a circle with a radius of 4.5 feet?

Back

A = π(4.5)² ≈ 63.585 ft².

Front

How does changing the radius affect the area of a circle?

Back

The area increases with the square of the radius; if the radius doubles, the area increases by a factor of four.

Front

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

Back

A = π(3)² ≈ 28.27 cm².