Chapter 9: Geometry - Circles and Regular Polygons

This video tutorial covers the calculation of the circumference and area of circles, as well as the area of regular polygons. It begins with an introduction to the topics and explains the formulas for circumference using diameter and radius. The video then demonstrates how to calculate the area of circles in terms of pi, using examples with given diameters and radii. Finally, it explains how to find the area of regular polygons using the apothem and perimeter, with examples involving different polygon types.

What topics are covered in this video?

• Area and circumference of circles, and area of regular polygons

• Area and perimeter of triangles

• Surface area of cubes

• Volume of cylinders

Which formula can be used to find the circumference of a circle?

• 2πr

• πd²

• πr²

• r²/2

If the diameter of a circle is 6 cm, what is its circumference?

• 3π cm

• 12π cm

• 6π cm

• 6 cm

What is the area of a circle with a radius of 5 meters in terms of π?

• 10π square meters

• 25π square meters

• 50π square meters

• 5π square meters

Given a circle with a diameter of 22 feet, what is its area in terms of π?

• 22π square feet

• 44π square feet

• 121π square feet

• 11π square feet

What is the formula for the area of a regular polygon?

• 1/2 × apothem × perimeter

• πr²

• 2πr

• side²

How do you find the perimeter of a regular polygon?

• Multiply the apothem by the number of sides

• Add the lengths of all sides

• Multiply the number of sides by the length of one side

• Divide the number of sides by the length of one side

What is the area of a regular polygon with an apothem of 3 yards and a side length of 7.5 yards?

• 56.25 square yards

• 112.5 square yards

• 56.25 square meters

• 28.125 square yards

How many sides does a hexagon have?

• 6

• 8

• 5

• 4

What is the area of an octagon with an apothem of 3 cm and a side length of 8.3 cm?

• 83.2 square cm

• 99.6 square cm

• 66.4 square cm

• 49.8 square cm