Chapter 7 Similarity
Definition: Ratio
The angles of a pentagon are in ratio 4:2:5:5:2, find the measure of each angle 4x+2x+5x+5x+2x = x = 540 x = , 60, 150, 150, 60
Definition: Proportion
Identify the means and extremes:
Definition: Geometric Mean A proportion in which the second and third terms are equal
Find the geometric mean between 5 and 28.
18 is the geometric mean between 7 and what number?
Properties of Proportions:
Definition: Similar Polygons Two polygons are similar iff, 1)Corresponding angles are congruent 2)Corresponding sides are in proportion
If ABCDE ~ NGPHM, then….
Ways to prove triangles similar: 1) AA~ theorem 2) SSS~ theorem 3) SAS~ theorem
AA~ theorem If two angles of one triangle are congruent to corresponding angles of another triangle, then the triangles are similar.
Find BE
How tall is the tree?
Given: BC // DE Prove: ∆ABC ~ ∆ADE
Triangle Proportionality Thm aka (side splitter thm)
Triangle Angle Bisector Thm