Overview

The purpose of this lesson is to use properties of similar polygons and proportions to find unknown measures.

This lesson will address the following CCRS Standard(s) for Geometry:

7.G.1: Solve problems involving scale drawings of geometric figures, including computing actual lengths and areas from a scale drawing and reproducing a scale drawing at a different scale
8.G.5: Use informal arguments to establish facts about the angle sum and exterior angles of triangles, above the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so

Directions

Complete 1.C Proportions and Similar Polygons homework assignment with 80% or better

In this lesson we have learned:

Given the proportion $\frac{a}{b} = \frac{c}{d}$ , we can solve by multiplying diagonals to get ad = bc.
If to polygons are similar, then corresponding sides are proportional
If two angles of one triangle are congruent to two angles of another triangle, then the triangle's sides are proportional.