Understanding the Area of a Circle

This video tutorial explains how to calculate the area of a circle using the formula pi r squared. It covers examples with both radius and diameter, demonstrating the step-by-step process of squaring the radius and multiplying by pi. The video also shows how to find the radius when the area is given, by dividing the area by pi and taking the square root. The tutorial concludes with a summary and directs viewers to additional resources for further learning.

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

• 2πr²

• πd

• πr²

• 2πr

When calculating the area of a circle, what should you do first?

• Square the radius

• Multiply the radius by pi

• Double the radius

• Divide the radius by pi

If a circle has a radius of 7 cm, what is the area in terms of pi?

• 21π

• 49π

• 14π

• 7π

How would you express the area of a circle with a radius of 7 cm to one decimal place?

• 155.0 cm²

• 154.0 cm²

• 153.9 cm²

• 150.0 cm²

What is the radius of a circle if its diameter is 8 cm?

• 2 cm

• 16 cm

• 4 cm

• 8 cm

Calculate the area of a circle with a diameter of 8 cm, rounded to one decimal place.

• 52.3 cm²

• 49.3 cm²

• 50.3 cm²

• 51.3 cm²

If the area of a circle is 50 cm², what is the first step to find the radius?

• Add pi

• Multiply by pi

• Square the area

• Divide by pi

After dividing the area by pi, what is the next step to find the radius?

• Square the result

• Multiply by 2

• Take the square root

• Subtract pi

What is the radius of a circle if its area is 50 cm², rounded to two decimal places?

• 3.99 cm

• 4.50 cm

• 4.00 cm

• 3.50 cm

What should you do if you are given the diameter and need to find the area of a circle?

• Use the diameter directly in the formula

• Subtract pi from the diameter

• Double the diameter

• Convert the diameter to radius first