Module 10 Lesson 1 - Circumference and Area

Front

What is the formula for the area of a circle?

Back

The area of a circle is calculated using the formula A = πr², where A is the area and r is the radius.

Front

What is the formula for the circumference of a circle?

Back

The circumference of a circle is calculated using the formula C = 2πr or C = πd, where C is the circumference, r is the radius, and d is the diameter.

Front

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

Back

Using the formula A = πr², the area is A = π(10)² = 100π cm² or approximately 314.16 cm².

Front

If a circle has a diameter of 20 cm, what is its circumference?

Back

Using the formula C = πd, the circumference is C = π(20) = 20π cm or approximately 62.83 cm.

Front

What is the value of π (pi) approximately?

Back

The value of π (pi) is approximately 3.14.

Front

How do you convert diameter to radius?

Back

The radius is half of the diameter. To find the radius, divide the diameter by 2.

Front

What is the area of a circle with a radius of 6 inches?

Back

Using the formula A = πr², the area is A = π(6)² = 36π in² or approximately 113.04 in².

Front

What is the circumference of a circle with a radius of 21 cm?

Back

Using the formula C = 2πr, the circumference is C = 2π(21) = 42π cm or approximately 131.9 cm.

Front

If the area of a circle is 254.34 cm², what is the radius?

Back

To find the radius, use the formula A = πr². Rearranging gives r = √(A/π). For A = 254.34, r ≈ 9 cm.

Front

What is the relationship between radius and diameter?

Back

The diameter is twice the length of the radius. d = 2r.