Answer:
- 21 square inches for lateral area
- 7 more square inches for the base
Explanation:
The regular tetrahedron Rachel wants to cover has four congruent triangular faces, each with a base of 4 inches and a height of 3.5 inches. The area of each face is given by the triangle area formula:
A = 1/2bh
Rachel's toy has triangular faces with an area of ...
A = 1/2(4 in)(3.5 in) = 7.0 in²
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Lateral Surfaces
The lateral surfaces consist of 3 of these triangles, so will have a total area of ...
3 × 7.0 in² = 21 in²
Paper to cover the lateral surfaces is about 21 square inches.
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Base
The base is congruent to the other sides, so will have the same area they do. To cover the base, Rachel need ...
about 7.0 more square inches