Post on 18-Jan-2018
description
Indirect Measurement
Warm-UpSolve each proportion.1. 3 X 2. 6 2.4
5 75 X 8
3. 9 X 4. X 8 27 6 3.5 7
= =
= =
X = 45 X = 20
X = 2 X = 4
What we are doing…
Learn to find measures indirectly by applying the properties of similar figures.
Indirect Measurement….
F
E G
A
B C
Notice how all angles are congruent.
A
B C
A
B
C
A
BC
A
B
A
B
C
Notice what happens as we turn the triangle.
Which angle corresponds with angle E?
Which angle corresponds with angle F?
BA
Example 1;Triangles ABC and EFG are similar.
Find the length of side EG.
B
A C
3 ft
4 ft
F
E G
9 ft
X
Triangles ABC and EFG are similar.
1. Vilma wants to know how wide the river near her house is. She drew a diagram and labeled it with her measurements. How wide is the river?
Question 1:
The diagram:
W
7 m
21 m
15 mWork…
Question 2:Julie wants to know how far it
is from her house to the big oak tree. She drew a diagram and labeled it with her known measurements. How far is the tree from her house?
Diagram….
5 ft
6 ft 4 ft
24 ft16 ft
Work…..
Question 3A yardstick casts a 2-ft shadow. At the
same time, a tree casts a shadow that is 6 ft long. How tall is the tree?
??
6 ft
3 ft
2 ft
Question 4;A 30 ft building casts a shadow that is
18 ft long. A nearby tree casts a shadow that is 3 ft long. How tall is the tree?
30 ft
18 ft 3 ft
?????
Question 5Triangles with triangles…
AC = 30DC = 20BE = 4AB = ?
E
B
D
C A
Question 6;
E
B
D
C A
AC = 24DC = ?BE = 8AB = 4