Math Problem Statement

If the total length of the edges of a regular triangular prism (equilateral triangular based prism) is 36 and the height is 6, find the surface area.

Solution

To find the surface area of the triangular prism, we first need to determine its dimensions and use those to calculate the total surface area. Let’s solve step by step:

Step 1: Understanding the total edge length

A regular triangular prism has:

  • 3 edges for the triangular base,
  • 3 edges for the other triangular base, and
  • 3 vertical edges connecting the two triangular bases.

Thus, there are a total of 3+3+3=93 + 3 + 3 = 9 edges.

Given that the total edge length is 3636, the length of one edge of the triangular base can be calculated as follows: 3side of base+3height=363 \cdot \text{side of base} + 3 \cdot \text{height} = 36 Substitute the given height (h=6h = 6): 3s+3(6)=363s + 3(6) = 36 3s+18=363s + 18 = 36 3s=18s=63s = 18 \quad \Rightarrow \quad s = 6 So, the side length of the equilateral triangle is s=6s = 6.

Step 2: Surface area of the prism

The surface area of a triangular prism is given by: Surface Area=2Base Area+Lateral Area\text{Surface Area} = 2 \cdot \text{Base Area} + \text{Lateral Area}

(a) Area of the triangular base

The formula for the area of an equilateral triangle is: Base Area=34s2\text{Base Area} = \frac{\sqrt{3}}{4} s^2 Substitute s=6s = 6: Base Area=34(62)=3436=93\text{Base Area} = \frac{\sqrt{3}}{4} (6^2) = \frac{\sqrt{3}}{4} \cdot 36 = 9\sqrt{3}

(b) Lateral area

The lateral area is the sum of the areas of the three rectangular sides. Each rectangle has a base s=6s = 6 and height h=6h = 6: Area of one rectangle=sh=66=36\text{Area of one rectangle} = s \cdot h = 6 \cdot 6 = 36 Lateral Area=336=108\text{Lateral Area} = 3 \cdot 36 = 108

(c) Total surface area

Now, substitute the values: Surface Area=2Base Area+Lateral Area\text{Surface Area} = 2 \cdot \text{Base Area} + \text{Lateral Area} Surface Area=293+108\text{Surface Area} = 2 \cdot 9\sqrt{3} + 108 Surface Area=183+108\text{Surface Area} = 18\sqrt{3} + 108

Thus, the surface area of the triangular prism is: 183+108square units\boxed{18\sqrt{3} + 108 \, \text{square units}}

Do you want further details or have any questions?

Here are 5 related questions to explore:

  1. How is the formula for the area of an equilateral triangle derived?
  2. What changes if the prism is not regular but scalene?
  3. Can you calculate the volume of this prism using the given dimensions?
  4. How would the surface area change if the height doubled?
  5. What is the significance of the lateral area in practical applications?

Tip: Always confirm the dimensions are consistent (e.g

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Math Problem Analysis

Mathematical Concepts

Geometry
Surface Area
Equilateral Triangles
Prisms

Formulas

Surface Area of a Prism = 2 × Base Area + Lateral Area
Area of an Equilateral Triangle = (sqrt(3) / 4) × s^2
Lateral Area = Perimeter of Base × Height

Theorems

Properties of Equilateral Triangles
Basic Geometric Relationships in Prisms

Suitable Grade Level

Grades 8-10