Question

Jada drew a net for a polyhedron and calculated its surface area.

She made some mistakes in her area calculation. Which calculation is incorrect?

For 14 points

Answer 1

The calculation of the area of the triangle is incorrect

Explanation:

To find the surface are of the net for the polyhedron, each area of the net will be calculated. There are 2 rectangles, 1 square, and 2 triangles that made up the net of the polyhedron.

To find out which calculation is incorrect, let's do our own calculation and compare with what Jada has:

Area of rectangle = lenght * width

Area of rectangle with lenght: 5 cm, width: 4cm

Area = 5*4 = 20 cm²

Area of square with side: 4 cm,

Area = 4² = 16 cm²

Area of rectangle with lenght: 4 cm, width: 3cm

`Area = 4*3 = 12 cm^2`

The 2 triangles have the same dimensions:

Height = 3 cm

Base = 4 cm

Area of triangle = ½*base*height

Area of each triangle = ½*4*3 = 2*3 = 6 cm²

This is different from what Jada calculated. Jada's calculation for the area of each of the triangles is incorrect. The area should be 6 cm² not 12 cm².

Surface area of the net = 20 + 16 + 12 + 2(6) = 60 cm²