Question

Beth enlarged the triangle below by a scale of 5. Height 3.5 cm, width 4cm. She found the area of the enlarged triangle. Her work is shown below. 1/2(4)(3.5)(5)= 35 cm2What was beth’s error?

Answer 1

Beth incorrectly applied the scale factor only to the product of the base and height of the original triangle instead of scaling both base and height separately and then computing the area.

Step-by-step explanation:

Beth's error was not correctly applying the scale factor to both the base and the height of the triangle before attempting to find the enlarged area. When enlarging geometric figures, each linear dimension should be multiplied by the scale factor. Thus, the enlarged base should be 4cm × 5 = 20cm and the enlarged height should be 3.5cm × 5 = 17.5cm. Then, to find the area of the enlarged triangle, she should use the formula 1/2 × base × height, which would yield 1/2 × 20cm × 17.5cm = 175cm2.