Area of a Circle

Front

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

Back

Area = π × r², where r is the radius.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

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

Back

154 cm² (Area = π × 7² = 3.14 × 49).

Front

What is the radius of a circle with a diameter of 20 cm?

Back

The radius is 10 cm (Radius = Diameter / 2).

Front

How do you find the area of a circle if you only know the diameter?

Back

Use the formula: Area = π × (Diameter/2)².

Front

What is the difference in the areas of two circles with radii 30 cm and 20 cm?

Back

1,570 cm² (Area of larger circle - Area of smaller circle).

Front

What is the radius of a circle?

Back

A line segment from the center of the circle to any point on its circumference.

Front

If a circle has an area of 78.5 cm², what is its radius?

Back

5 cm (Area = π × r², so r = √(Area/π)).

Front

What is the area of a circle with a radius of 5 cm?

Back

78.5 cm² (Area = π × 5² = 3.14 × 25).

Front

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

Back

The area increases by a factor of four (Area = π × (2r)² = 4πr²).