Understanding Composite Figures: Rectangles and Semicircles

This video tutorial explains how to calculate the area of composite figures, specifically a rectangle and a semicircle. It covers the necessary formulas for each shape and demonstrates the calculation process through two examples. The tutorial emphasizes understanding the relationship between diameter and radius and the importance of unit consistency in area calculations.

What is the formula for the area of a rectangle?

• Length x Width x Height

• Length + Width

• Length x Width

• 2 x (Length + Width)

How do you calculate the diameter if the radius is known?

• Radius / 2

• Radius x 2

• Radius - 2

• Radius + 2

What is the formula for the area of a semicircle?

• Pi x Diameter

• 1/2 x Pi x Diameter

• 1/2 x Pi x Radius^2

• Pi x Radius^2

If the radius of a semicircle is 3 cm, what is the diameter?

• 12 cm

• 9 cm

• 6 cm

• 3 cm

What is the total area of a rectangle with dimensions 9 cm by 6 cm and a semicircle with radius 3 cm?

• 68.13 cm²

• 54 cm²

• 82.39 cm²

• 28.26 cm²

In the second example, what is the length of the rectangle?

• 4 cm

• 8 cm

• 10 cm

• 6 cm

How do you find the width of the rectangle in the second example?

• Using the radius of the semicircle

• Using the length of the rectangle

• Using the area of the semicircle

• Using the given width

What is the area of the semicircle in the second example if the radius is 4 cm?

• 16 cm²

• 32 cm²

• 50.24 cm²

• 25.12 cm²

What is the total area of the composite figure in the second example?

• 114.36 cm²

• 64 cm²

• 50.24 cm²

• 89.12 cm²

Why is the area always expressed in square units?

• Because it represents a two-dimensional space

• Because it is easier to calculate

• Because it is a three-dimensional space

• Because it is a convention