Math Problem Statement

The diagram shows a triangular prism. Calculate the volume, the length of the slanted side, and the total surface area.

Solution

Let's solve the questions step by step for the triangular prism shown in the diagram.

Given information:

  • The triangular base has a height of 29cm29 \, \text{cm} and a base of 34cm34 \, \text{cm}.
  • The length of the prism is 38cm38 \, \text{cm}.

Step (i) Calculate the volume of the prism:

The volume of a prism is given by:

V=Base Area×LengthV = \text{Base Area} \times \text{Length}

The base area of the triangular face is:

Base Area=12×base of triangle×height of triangle\text{Base Area} = \frac{1}{2} \times \text{base of triangle} \times \text{height of triangle}

Substitute the known values:

Base Area=12×34cm×29cm=493cm2\text{Base Area} = \frac{1}{2} \times 34 \, \text{cm} \times 29 \, \text{cm} = 493 \, \text{cm}^2

Now, calculate the volume:

V=493cm2×38cm=18,734cm3V = 493 \, \text{cm}^2 \times 38 \, \text{cm} = 18,734 \, \text{cm}^3

So, the volume of the prism is 18,734 cm³.

Step (ii) Calculate the length of the slanted side of the triangle:

To find the slanted side (hypotenuse) of the triangle, we can use the Pythagorean theorem:

c2=a2+b2c^2 = a^2 + b^2

Where:

  • a=29cma = 29 \, \text{cm} (height),
  • b=17cmb = 17 \, \text{cm} (half of the base, i.e., 342\frac{34}{2}).

Substitute the values:

c2=292+172=841+289=1130c^2 = 29^2 + 17^2 = 841 + 289 = 1130

c=113033.63cmc = \sqrt{1130} \approx 33.63 \, \text{cm}

So, the length of the slanted side is approximately 33.63 cm.

Step (iii) Calculate the total surface area of the prism:

The surface area consists of:

  • The area of the two triangular faces,
  • The area of the three rectangular faces.
  1. Area of the triangular faces (2 identical triangles): Area of one triangle=493cm2\text{Area of one triangle} = 493 \, \text{cm}^2 For two triangles: 2×493=986cm22 \times 493 = 986 \, \text{cm}^2

  2. Area of the rectangular faces:

    • Front face: base of the triangle×length=34×38=1292cm2\text{base of the triangle} \times \text{length} = 34 \times 38 = 1292 \, \text{cm}^2
    • Bottom face: slanted side×length=33.63×38=1277.94cm2\text{slanted side} \times \text{length} = 33.63 \times 38 = 1277.94 \, \text{cm}^2
    • Back face: height of the triangle×length=29×38=1102cm2\text{height of the triangle} \times \text{length} = 29 \times 38 = 1102 \, \text{cm}^2

Now, sum these areas:

Total Surface Area=986+1292+1277.94+1102=4657.94cm2\text{Total Surface Area} = 986 + 1292 + 1277.94 + 1102 = 4657.94 \, \text{cm}^2

So, the total surface area is approximately 4657.94 cm².


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Math Problem Analysis

Mathematical Concepts

Geometry
Prism
Surface Area
Volume
Pythagoras' Theorem

Formulas

Volume of prism = Base Area × Length
Base Area of triangle = 1/2 × base × height
Pythagoras' Theorem: c² = a² + b²
Surface Area = Area of 2 triangles + Area of 3 rectangles

Theorems

Pythagoras' Theorem

Suitable Grade Level

Grades 7-10