Chapter 10 - Similarity

By: Ashley and Rachele

Section 10-1

• A proportion is a statement that two ratios are equal.

• Example: a:b = c:d

• To prove 2 polygons similar, corresponding angles must all be congruent and size must be proportionate.

Section 10-2 Proving Triangles Similar

• AA, SAS, SSS• If two angles of one triangle are congruent to two

angles of another triangle then the triangles are similar. – AA

• If an angle of one triangle is congruent to an angle of a second triangle, and the sides including the two angles are proportional, then the triangles are similar. – SAS

• If the corresponding sides of two triangles are proportional, then the triangles are similar. - SSS

Section 10-3

• Geometric mean !

Section 10-4 proportions and similar triangles

Slide Splitter Proportions

Angle Bisector Proportion

Section 10-5 / 10-6• Similarity ratios2 : 6 1 : 3Perimeter ratio 8 : 241 : 3Area ratio (in2)4 : 36 (in3)1 : 9Volume ratio (in3)8 : 2161 : 27

Candy Geometry Land !

1. Which of the following is this showing?

A.SASB.SSSC.AAD.None

2. What is the geometric mean of 8 & 18 ?

A.+/- 12B. 12C. +/- 144D. 144

A.SASB.SSSC.AAD.None

3. Which of the following is this showing?

4. Can you use SAS to prove that the triangles pictured below similar?

A. YesB. No

5. What is the value of x?

A.18B.2C.3D.24

6. Are the following polygons similar?

A. YesB. No

If you couldn’t get those, well that is sad ): No offense!

LOOK AT THE BRIGHT SIDE YOUR HALF WAY DONE WITH THE QUESTIONS (:

7.

8. Solve for the variables

9. If a 5 ft. 3in. man is casting a 6 ft. shadow and a building is casting a 20 ft. shadow.

How tall is the building?

10.

Solve for x.

EASY BONUS

SIKE!

BAM!, FIN.