Math Problem Statement

Find the area in cm² of the given composite shape consisting of a semicircle, rectangle, and right triangle.

Solution

To find the area of the given composite shape, I will break it into simpler shapes and calculate the area of each part separately:

Step-by-step solution:

  1. Divide the shape into components:

    • A semicircle (top left).
    • A rectangle (bottom middle).
    • A right triangle (right side).
  2. Calculate the area of each shape:

    • Semicircle: The diameter is 4 cm, so the radius r=42=2r = \frac{4}{2} = 2 cm. The area of a full circle is πr2\pi r^2, so the area of the semicircle is: Area of semicircle=12π(2)2=12π(4)12×12.57=6.28cm2\text{Area of semicircle} = \frac{1}{2} \pi (2)^2 = \frac{1}{2} \pi (4) \approx \frac{1}{2} \times 12.57 = 6.28 \, \text{cm}^2

    • Rectangle: The width is 4 cm and the height is 2 cm. Area of rectangle=4×2=8cm2\text{Area of rectangle} = 4 \times 2 = 8 \, \text{cm}^2

    • Right triangle: The base is 5 cm and the height is 2 cm. Area of triangle=12×5×2=12×10=5cm2\text{Area of triangle} = \frac{1}{2} \times 5 \times 2 = \frac{1}{2} \times 10 = 5 \, \text{cm}^2

  3. Total area: Add the areas of all three parts: Total area=6.28+8+5=19.28cm2\text{Total area} = 6.28 + 8 + 5 = 19.28 \, \text{cm}^2

The closest correct choice is 19.79 cm².

Would you like more explanation on any part of the solution?

Related Questions:

  1. How do you find the area of composite shapes with different curves?
  2. What are other ways to calculate the area of a triangle with different dimensions?
  3. How can you approximate the value of π more accurately?
  4. What techniques can simplify complex area calculations?
  5. What are common mistakes when finding areas of composite shapes?

Tip: Always break down complex shapes into simpler parts to make calculations easier.

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Math Problem Analysis

Mathematical Concepts

Geometry
Composite Shapes
Area Calculation

Formulas

Area of a semicircle: (1/2)πr²
Area of a rectangle: base × height
Area of a right triangle: (1/2) × base × height

Theorems

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Suitable Grade Level

Grades 6-8