Math Problem Statement

The figure shows a semicircle and a rectangle from which a triangle has been cut. Find the area of the figure. (Use 3.14 for π)

Solution

The image shows a figure consisting of a semicircle and a rectangle with a triangle cut out of it. We are tasked with finding the area of the figure, using π=3.14\pi = 3.14.

Given measurements:

  • Length of the rectangle: 30m30 \, \text{m}
  • Width of the rectangle: 12m12 \, \text{m}
  • The semicircle is on the left, with a diameter equal to the width of the rectangle: 12m12 \, \text{m}
  • The triangle is right-angled, with the base of 10m10 \, \text{m} and the height matching the width of the rectangle (12m12 \, \text{m}).

Steps to solve:

  1. Area of the rectangle: Area of the rectangle=Length×Width=30m×12m=360m2\text{Area of the rectangle} = \text{Length} \times \text{Width} = 30 \, \text{m} \times 12 \, \text{m} = 360 \, \text{m}^2

  2. Area of the semicircle: The diameter of the semicircle is 12m12 \, \text{m}, so the radius is 6m6 \, \text{m}. Area of the semicircle=12πr2=12×3.14×62=12×3.14×36=56.52m2\text{Area of the semicircle} = \frac{1}{2} \pi r^2 = \frac{1}{2} \times 3.14 \times 6^2 = \frac{1}{2} \times 3.14 \times 36 = 56.52 \, \text{m}^2

  3. Area of the triangle: The triangle is right-angled with base 10m10 \, \text{m} and height 12m12 \, \text{m}. Area of the triangle=12×base×height=12×10m×12m=60m2\text{Area of the triangle} = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 10 \, \text{m} \times 12 \, \text{m} = 60 \, \text{m}^2

  4. Total area of the figure: Total area=Area of the rectangle+Area of the semicircleArea of the triangle\text{Total area} = \text{Area of the rectangle} + \text{Area of the semicircle} - \text{Area of the triangle} Total area=360m2+56.52m260m2=356.52m2\text{Total area} = 360 \, \text{m}^2 + 56.52 \, \text{m}^2 - 60 \, \text{m}^2 = 356.52 \, \text{m}^2

Final Answer:

The area of the figure is 356.52m2356.52 \, \text{m}^2.

Do you need further details or have any questions?


Here are 5 related questions to expand on this:

  1. How do we calculate the circumference of a semicircle?
  2. What is the perimeter of the entire figure if we include the triangle's cut-out?
  3. How would the calculation change if the triangle were not right-angled?
  4. What formula is used to find the area of a full circle?
  5. How can we derive the formula for the area of a right-angled triangle?

Tip: In geometry, breaking complex shapes into simpler ones like rectangles, triangles, and circles often simplifies area calculations.

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Math Problem Analysis

Mathematical Concepts

Geometry
Area Calculation
Composite Shapes

Formulas

Area of a rectangle = length × width
Area of a semicircle = (1/2) × π × radius^2
Area of a right-angled triangle = (1/2) × base × height

Theorems

Basic Area Theorem for Composite Shapes

Suitable Grade Level

Grades 7-10