Area of Circles: Formula and Calculations

The video tutorial explains the concept of area, focusing on circles. It introduces the formula for calculating the area of a circle, pi r squared, and demonstrates how to derive this formula by rearranging circle sectors into a rectangle. The tutorial provides practical examples of using the formula to calculate the area when given the radius or diameter and explains how to work backwards from a given area to find the radius or diameter. It emphasizes the importance of understanding and memorizing the formula, and offers tips for converting results into decimal form.

What is the formula for calculating the area of a circle?

• r²/π

• πr²

• 2πr

• πd²

How is the formula for the area of a circle derived?

• By dividing a circle into triangles

• By using the diameter directly

• By rearranging circle sectors into a rectangle

• By calculating the circumference

If a circle has a radius of 4 cm, what is its area?

• 16π cm²

• 8π cm²

• 50.27 cm²

• 25π cm²

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

• Square the diameter

• Halve the diameter to find the radius

• Double the diameter to find the radius

• Use the diameter directly in the formula

How can you find the radius if the area of a circle is given?

• Square the area and divide by π

• Multiply the area by π

• Divide the area by π and then square root

• Add π to the area

What is the diameter of a circle if its radius is 10.555 cm?

• 10.555 cm

• 21.11 cm

• 5.2775 cm

• 31.665 cm

Why is it important to understand the formula for the area of a circle?

• It helps in calculating the circumference

• It is used to find the volume of a sphere

• It is frequently given in exams

• It is not provided in tests, so must be memorized