1. Section 2

1.28. Explore 2

Mathematics 20-3 Module 5

Section 2: Perspective and Scale

 

Example

 

This is a photo of the pyramid of Khafre at Giza.

AbleStock.com/Thinkstock

It is not likely that a full-scale model of the Pyramid of Khafre at Giza will ever be built. This pyramid was built with a square base of approximately 215 m on each side and the slant height of each triangular face is approximately 180 m.

  1. If a 1:2000 scale model were constructed, how long, to the nearest millimetre, would each side of the square base be?
  1. To the nearest millimetre, what would the slant height be for each triangular face in the model?

Solution

 

Description of Step
  1. Find the side length of the scale model.
  1. Find the slant height of the scale model.

To use the scale of 1:2000, you need to have all measurements in the same units—millimetres will work well.

 

Convert the side length to millimetres.

  • Remember that 1 m = 1000 mm.

Identify the ratios that relate the scale to the actual model lengths.

  • Let s represent the scale model square base length.

  • Let x represent the scale model slant height.
s: 215 000 = 1:2000 x: 180 000 = 1:2000

Set up a proportion and solve for s and x.

 

Each side of the model’s square base would be about 108 mm and the slant height would be 90 mm.