Transcript Unit 8 Lesson 9.4A Special Right Triangles

Unit 8 Lesson 9.4B
Special Right Triangles
CCSS
Lesson Goals
G-SRT 8: Use trigonometric
• Use the special right triangle
ratios and the Pythagorean
theorems to find missing side
Theorem to solve right
lengths in polygons.
triangles in applied problems.
G-SRT 8.1: Derive and use the
trigonometric ratios for
special right triangles
(30°,60°,90°and 45°,45°,90°).
ESLRs: Becoming Effective Communicators,
Competent Learners and Complex Thinkers
PREVIOUSLY ON
GEOMETRY
• The Pythagorean Theorem is used to find
missing side lengths in right triangles.
• Isosceles triangles have two congruent sides
and two congruent angles.
17
8
b
Example
An equilateral triangle has a side length of 8 feet.
Estimate the area.
A  12 bh
8 ft 30

1
2
8h 

1
2
8  4
h
60
4 ft
h4 3
 16 3 ft
 27.7 ft 2
3
2

Example
A hexagonal Ferris wheel is made up of 6 congruent
equilateral triangles. Find the area of the entire Ferris
wheel.
AD = 12 bh
20 ft
20 ft 30
h
60
10 ft
h = 10 3
» 6 (173.2 ) » 1,039.2 ft
2
( 20h)
= 12 ( 20 ) (10
=
1
2
= 100 3 ft 2
» 173.2 ft
2
3
)
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