File

Report
Warm-up
• Make sure to grab a red pen and be ready to
grade your homework
Today
Grade homework
Squawk like a CHICKEN!
Discussion
Practice problems
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
7.6: Indirect Measurement and
Additional Similarity Theorems
Obj: _______________________
___________________________
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
Indirect Measurement
• Measuring the distance of something without
physically measuring it
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
Using Similar Triangles to Measure
Distance
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
8.5 Indirect Measurement and Additional Similarity Theorems
Key Skills
Use similar triangles to measure distance
indirectly.
Estimate the width of the lake.
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
Finding Distance Indirectly
ROCK CLIMBING
are at an
indoor
climbing
wall.
To estimate
of
SimilarYou
triangles
can
be used
to find
distances
thatthe
areheight
difficult
the wall, youto
place
a mirror
on the floor 85 feet from the base of the wall. Then
measure
directly.
you walk backward until you can see the top of the wall centered in the mirror.
You are 6.5 feet from the mirror and your eyes are 5 feet above the ground.
D
B
5 ft
Not drawn to scale
A
6.5 ft
C
85 ft
E
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
Finding Distance Indirectly
Use similar triangles to estimate
the height of the wall.
SOLUTION
DE EC
Ratios of lengths of
=
corresponding sides are equal.
BA AC
So,
the height of the wall is about 65 feet.
DE = 85
Substitute.
5
6.5
D
Multiply each side by
5 and simplify.
65.38  DE
B
5 ft
A
6.5 ft
C
85 ft
E
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
Using shadows
• Kim wants to know the height of a basketball
hoop. The regulation height is 10 ft. Use
Kim’s height and length of the shadows to
find the height of the basketball hoop. Is the
hoop at regulation height?
• She is 70” and casts a 50” shadow, the
basketball hoop casts a 85” shadow.
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
• At a certain time of day, a 6ft man casts a 4 ft
shadow. At the same time of day, how tall is
a tree that casts an 18 ft shadow?
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.
Copyright © by Holt, Rinehart and Winston. All Rights Reserved.

similar documents