Chapter 4: Scale Factors and Similarities

enlargement

* an increase in the dimensions of an object by a constant factor

reduction

* a decrease in the dimensions of an object by a constant factor
* opposite of enlargement

scale factor

* the constant factor by which all dimensions of an object are enlarged or reduced in a scale drawing

scale

* a comparison between the actual size of an object and the size of its image
* expressed as a ratio, fraction, percent, diagram or words
* eg. 1:50 on a map, 1cm meaning 50km

scale diagram

* a diagram that is similar to the actual figure or object
* must be the same proportions but can be smaller or larger

proportion

* an equation that says that two ratios or two rates are equal
* written as a fraction or ratio form

corresponding angles

* angles that have the same relative position in two geometric figures

corresponding sides

* sides that have the same relative position in two geometric figures

similar

* figures that have the same shape, but different size

polygon

* a two-dimensional closed figure made of three or more line segments

congruent

* identical in shape and size

origin

* the initial point or the starting point from where calculations or measurements

prime number

* number in which the only factor is 1 and itself