Circle Geometry Concepts

This video tutorial covers the calculation of the area of a circle, starting with a review of circumference and moving on to finding the radius from the circumference. It includes practical examples such as calculating the area covered by a sprinkler and determining waste from a circular table project. The tutorial also explains how to calculate both exact and approximate areas using different values for pi.

What is the formula to find the radius of a circle if the circumference is known?

• C = 2πr

• C = πd

• r = C/2π

• r = C/π

How is the area of a circle derived from its circumference?

• By using the formula A = πr²

• By rearranging the circle into a rectangle

• By multiplying the radius by the circumference

• By dividing the circumference by the diameter

What is the formula for the area of a circle?

• A = 2πr

• A = πr²

• A = 2πd

• A = πd

What is the area of a circle with a radius of 12 feet?

• 144π square feet

• 452π square feet

• 144 square feet

• 452 square feet

If a circular table is cut from a square piece of wood, how do you calculate the waste material?

• Subtract the area of the circle from the area of the square

• Add the area of the circle to the area of the square

• Divide the area of the square by the area of the circle

• Multiply the area of the circle by the area of the square

What is the exact area of a circle with a radius of 2 cm?

• 4π cm²

• 8π cm²

• 12.56 cm²

• 6.28 cm²

How do you find the approximate area of a circle using 3.14 for π?

• Add 3.14 to the radius

• Multiply the radius by 3.14

• Divide the radius by 3.14

• Square the radius and multiply by 3.14

What is the area of a circle with a radius of 4 cm, using 22/7 as an approximation for π?

• 44 cm²

• 50 cm²

• 154 cm²

• 49 cm²

What is the circumference of a circle with a radius of 7 cm, expressed in terms of π?

• 7π cm

• 21π cm

• 28π cm

• 14π cm

How do you express the area of a circle in terms of π for exactness?

• Use the decimal approximation of π

• Leave π in the expression

• Convert π to a fraction

• Round π to the nearest whole number