Math Problem Statement

Paman merencanakan membuat tenda tanpa alas seperti pada gambar dengan harga kain Rp100.000, per m², tentukan a. Luas tenda b. Biaya pembelian kain.

Solution

The image provided shows a tent design, and the task is to calculate:

a. The surface area of the tent
b. The cost of purchasing the fabric, given that the fabric costs Rp100,000 per square meter

Step-by-Step Calculation:

a. Surface Area of the Tent

The tent is shaped like a combination of a rectangular base and a pyramid-like roof. Based on the given dimensions:

  • Base dimensions: 8m by 8m (a square base).
  • Height of the vertical walls: 2m.
  • Slant height of the roof (side triangle faces): 5m.
1. Area of the four vertical walls:

These walls are rectangular, and their height is 2 meters. For each side:

  • 2 vertical walls (width of 8m):
    Area of each = 8m×2m=16m28 \, \text{m} \times 2 \, \text{m} = 16 \, \text{m}^2
    Total for both walls = 16×2=32m216 \times 2 = 32 \, \text{m}^2

  • 2 vertical walls (width of 8m):
    Area of each = 8m×2m=16m28 \, \text{m} \times 2 \, \text{m} = 16 \, \text{m}^2
    Total for both walls = 16×2=32m216 \times 2 = 32 \, \text{m}^2

Total for all vertical walls = 32+32=64m232 + 32 = 64 \, \text{m}^2.

2. Area of the roof:

The roof consists of 4 triangular faces. Each triangle has:

  • Base: 8 meters
  • Height (slant height): 5 meters

The area of one triangular face = 12×8m×5m=20m2\frac{1}{2} \times 8 \, \text{m} \times 5 \, \text{m} = 20 \, \text{m}^2

There are 4 such triangular faces, so total area of the roof = 4×20=80m24 \times 20 = 80 \, \text{m}^2.

3. Total surface area of the tent:

Total surface area = area of vertical walls + area of the roof
= 64+80=144m264 + 80 = 144 \, \text{m}^2.

b. Cost of purchasing the fabric

Given the fabric costs Rp100,000 per square meter, the total cost will be:

Cost=144m2×100,000Rp/m2=14,400,000Rp\text{Cost} = 144 \, \text{m}^2 \times 100,000 \, \text{Rp/m}^2 = 14,400,000 \, \text{Rp}

Final Answer:

  • a. Surface area of the tent: 144 m²
  • b. Cost of purchasing fabric: Rp 14,400,000

Would you like more details on any step?

Here are 5 related questions you might find helpful:

  1. How do you calculate the surface area of a triangle with different dimensions?
  2. How would the calculation change if the tent had a floor?
  3. What is the difference between slant height and vertical height in a pyramid?
  4. How can we calculate the fabric cost if the price changes?
  5. How can we determine the amount of fabric if a seam allowance is needed?

Tip: Always double-check the slant height and base dimensions when calculating the surface area of pyramidal structures.

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Math Problem Analysis

Mathematical Concepts

Geometry
Surface Area Calculation

Formulas

Area of a rectangle = length × width
Area of a triangle = 0.5 × base × height

Theorems

Surface Area Calculation for Composite Shapes

Suitable Grade Level

Grades 7-9