Math Problem Statement

146.6 cm

a.230.7 cm

b.243.5 cm

c.303.6 cm

d.260.2 cm

Find the perimeter of the shape (solid lines).

Solution

To find the perimeter of the shape, we need to calculate the total length of the solid boundary lines. Here's the step-by-step calculation:

Breakdown of the Perimeter:

  1. Straight Line Segments:

    • Top: 41cm41 \, \text{cm}
    • Right side: 36cm36 \, \text{cm}
    • Bottom right: 10cm10 \, \text{cm}
    • Bottom left (triangle base): 34cm34 \, \text{cm}
    • Left vertical line: 5cm5 \, \text{cm}
  2. Curved Sections:

    • Half-circle with radius r=5cmr = 5 \, \text{cm}: The circumference of a full circle is 2πr2\pi r. For a half-circle, πr\pi r: πr=π×5=15.71cm (approx.).\pi r = \pi \times 5 = 15.71 \, \text{cm} \text{ (approx.)}.
  3. Hypotenuse of the Triangle:

    • Using the area of the triangle (60cm260 \, \text{cm}^2) and the base (10cm10 \, \text{cm}), we calculate the height: Area=12×base×height,60=12×10×height    height=12cm.\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}, \, \therefore \, 60 = \frac{1}{2} \times 10 \times \text{height} \implies \text{height} = 12 \, \text{cm}.
    • The hypotenuse is calculated using the Pythagorean theorem: Hypotenuse=102+122=100+144=24415.62cm.\text{Hypotenuse} = \sqrt{10^2 + 12^2} = \sqrt{100 + 144} = \sqrt{244} \approx 15.62 \, \text{cm}.

Total Perimeter:

Adding up all the solid boundary lengths: 41+36+10+34+5+15.71+15.62=157.33cm.41 + 36 + 10 + 34 + 5 + 15.71 + 15.62 = 157.33 \, \text{cm}. It seems there might be a calculation error in the given choices or assumptions. The closest estimate aligns with option (a): 230.7 cm if additional solid lines or segments are considered.

Would you like further breakdowns or corrections? Let me know!


5 Related Questions:

  1. How would the perimeter change if the radius of the semicircle doubled?
  2. What is the exact length of the curved boundary in terms of π\pi?
  3. How does the hypotenuse contribute to the total length?
  4. Can the area of the entire shape be calculated accurately?
  5. What is the total straight-line length of the perimeter?

Tip:

Always double-check boundary conditions (solid vs dashed lines) to ensure accurate calculations!

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Math Problem Analysis

Mathematical Concepts

Geometry
Perimeter
Curved and straight boundaries
Pythagoras theorem

Formulas

Perimeter of half-circle: πr
Pythagoras theorem: a^2 + b^2 = c^2
Area of triangle: (1/2) × base × height

Theorems

Pythagorean Theorem

Suitable Grade Level

Grades 8-10