University:
California State University, Northridge
Course:
MATH 370 | Foundations of Geometry
Academic year:

2024
Views:

387

Pages:

2
Author:

inao6uk

Two triangles are said to be similar if their corresponding angles are congruent. For example the following two triangles are similar: If two triangles are similar then the length of their sides are proportional. That means that if for example one side of the larger triangle is three times as long as the corresponding side (across from the same size angle) of the smaller triangle then all the sides of the larger triangle are three times as large of their corresponding parts in the smaller triangle. This fact allows us to find missing parts of similar triangles by setting up proportions and cross multiplying. Refresher on Cross multiplying: If we have two fractions that are equal to each other we are allowed to multiply the numerator of one fraction with the denominator of the second fraction and set the result equal to the product of the denominator of the first fraction and the numerator of the second fraction. For example: 15x = (10)(6) 15x = 60 x = 4. (Since (15)(4) = 60) Note that we are only allowed to do this if we have single fractions equal to each other. Example 1) Given AB || DE (parallel) AB = 24 AE = 5 EC = 15 Find DE. Since AB and DE are parallel the corresponding angles at the two lines are congruent (