1. D. N. A. 30 15 x 21 12 y 10 z
PQRS~ABCD
Find the scale factor of PQRS to ABCD.
Find the value of x.
Find the value of y.
Find the value of z.
Find the perimeter of PQRS.
Find the perimeter of ABCD.
Find the ratio of the perimeter of PQRS to the perimeter of ABCD.

2. SAS  Similarity Theorem
If one angle of one triangle is congruent to an angle of a second triangle and the lengths of the sides including these angles are proportional, then the triangles are similar. K J L Y X Z
ass
Pantograph

3. Prove RTS ~ PSQ S  S (reflexive prop.) SPQ  SRT SAS  ~ Thm. S5 15 12 4
SPQ  SRT
SAS  ~ Thm.

4. Are the two triangles similar?P Q R T 10 15 12 9
NQP  TQR
Not Similar

5. Determine the similar triangles.
5. Find x, AC, and ED.
6. Find x, JL, and LM.
7. Find x, EH, and EF.

6. Are Triangles Similar?
In the figure, , and ABC and DCB are right angles. Determine which triangles in the figure are similar.
Lesson 3 Ex1

7. In the figure, OW = 7, BW = 9, WT = 17. 5, and WI = 22. 5
In the figure, OW = 7, BW = 9, WT = 17.5, and WI = Determine which triangles in the figure are similar.
A. ΔOBW ~ ΔITW
B. ΔOBW ~ ΔWIT
C. ΔBOW ~ ΔTIW
D. ΔBOW ~ ΔITW
Lesson 3 CYP1

8. Parts of Similar Triangles
ALGEBRA Given , RS = 4, RQ = x + 3, QT = 2x + 10, UT = 10, find RQ and QT.
Lesson 3 Ex2

9. Parts of Similar Triangles
Since because they are alternate interior angles. By AA Similarity, ΔRSQ ~ ΔTUQ. Using the definition of similar polygons,
Substitution
Cross products
Lesson 3 Ex2

10. Parts of Similar Triangles
Distributive Property
Subtract 8x and 30 from each side.
Divide each side by 2.
Now find RQ and QT.
Answer: RQ = 8; QT = 20
Lesson 3 Ex2

11. INDIRECT MEASUREMENT On her trip along the East coast, Jennie stops to look at the tallest lighthouse in the U.S. located at Cape Hatteras, North Carolina. At that particular time of day, Jennie measures her shadow to be 1 feet 6 inches in length and the length of the shadow of the lighthouse to be 53 feet 6 inches. Jennie knows that her height is 5 feet 6 inches. What is the height of the Cape Hatteras lighthouse to the nearest foot?
A. 196 ft B ft
C. 441 ft D ft
Lesson 3 CYP3

12. Geometry – Practice Workbook Do not write in the workbook.
Write your answers on a separate sheet of paper.
Complete:
p. 43 #1 – 8 all
p. 42 #1 – 5 odd
p. 41 # 1 – 15 odd