Math Problem Statement

Find the area of the composite figure above. The area is ___ ft². (Use 3.14 for π. Do not round your answer or put units in your answer.)

Solution

To solve for the area of the composite figure, let's break it into parts:

Step 1: Identify the components

The figure consists of:

  1. A rectangle with dimensions:
    • Length = 15 ft
    • Height = 6 ft
  2. A semi-circle (half of a circle) with:
    • Diameter = 6 ft → Radius r=62=3r = \frac{6}{2} = 3 ft

The total area will be the sum of the rectangle's area and the semi-circle's area.


Step 2: Calculate the area of the rectangle

The formula for the area of a rectangle is: Arectangle=Length×WidthA_{\text{rectangle}} = \text{Length} \times \text{Width} Substitute the values: Arectangle=15×6=90ft2A_{\text{rectangle}} = 15 \times 6 = 90 \, \text{ft}^2


Step 3: Calculate the area of the semi-circle

The formula for the area of a full circle is: Acircle=πr2A_{\text{circle}} = \pi r^2 Since the semi-circle is half of a circle: Asemi-circle=12πr2A_{\text{semi-circle}} = \frac{1}{2} \pi r^2 Using π=3.14\pi = 3.14 and r=3r = 3: Asemi-circle=12×3.14×32A_{\text{semi-circle}} = \frac{1}{2} \times 3.14 \times 3^2 Simplify: Asemi-circle=12×3.14×9=28.262=14.13ft2A_{\text{semi-circle}} = \frac{1}{2} \times 3.14 \times 9 = \frac{28.26}{2} = 14.13 \, \text{ft}^2


Step 4: Add the areas

Now, add the areas of the rectangle and the semi-circle: Atotal=Arectangle+Asemi-circleA_{\text{total}} = A_{\text{rectangle}} + A_{\text{semi-circle}} Atotal=90+14.13=104.13ft2A_{\text{total}} = 90 + 14.13 = 104.13 \, \text{ft}^2


Final Answer:

The area of the composite figure is: 104.13ft2\boxed{104.13 \, \text{ft}^2}


Let me know if you want further clarifications or a step-by-step breakdown of any part!

Related Questions:

  1. How do you calculate the perimeter of this composite figure?
  2. How would the area change if the rectangle’s dimensions were doubled?
  3. What is the area of a full circle with a radius of 3 ft?
  4. How do you find the area of a composite figure with more parts, such as triangles or trapezoids?
  5. If the radius of the semi-circle were increased to 5 ft, how would the total area change?

Tip: Always divide complex figures into basic shapes (like rectangles, triangles, and circles) to simplify area calculations.

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Math Problem Analysis

Mathematical Concepts

Geometry
Composite Figures
Area of Rectangle
Area of Semi-Circle

Formulas

Area of Rectangle = Length × Width
Area of Circle = πr²
Area of Semi-Circle = 1/2 × πr²

Theorems

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Suitable Grade Level

Grades 6-8