Nets Math Example 3

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Example 3

easy
How many faces does a triangular prism have, and what shapes are they? If the triangular base has base 44 cm and height 33 cm, and the prism length is 1010 cm, find the surface area using a net.

Solution

  1. 1
    Step 1: A triangular prism has 5 faces: 2 triangular faces (bases) and 3 rectangular faces (lateral faces).
  2. 2
    Step 2: Area of each triangular base: 12(4)(3)=6\frac{1}{2}(4)(3) = 6 cm². Both triangular faces: 2×6=122 \times 6 = 12 cm².
  3. 3
    Step 3: The three rectangular lateral faces have widths equal to the three sides of the triangle. If the triangle has sides 4, 3, and hypotenuse 16+9=5\sqrt{16+9} = 5 cm (right triangle), the lateral areas are 4×10=404 \times 10 = 40, 3×10=303 \times 10 = 30, and 5×10=505 \times 10 = 50 cm².
  4. 4
    Step 4: Total SA =12+40+30+50=132= 12 + 40 + 30 + 50 = 132 cm².

Answer

5 faces (2 triangles + 3 rectangles); SA=132SA = 132 cm²
The net of a triangular prism unfolds to show 2 triangles and 3 rectangles. Computing each face's area and summing gives the total surface area of 132 cm². The right triangle base (3-4-5) has sides that determine the three rectangle widths.

About Nets

A net is a two-dimensional layout of all the faces of a three-dimensional solid, arranged so that folding along the edges produces the original solid. Nets reveal the surface area as the sum of flat face areas.

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