11/27/20158-2: special right triangles1 g1.2.4: prove and use the relationships among the side...
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04/18/2304/18/23 8-2: Special Right Triangles8-2: Special Right Triangles 11
8-2: Special Right Triangles
G1.2.4: Prove and use the relationships among the side lengths and the angles of 30°- 60°- 90° triangles and 45°- 45°- 90° triangles.
L1.1.6: Explain the importance of the irrational numbers √2 and √3 in basic right triangle trigonometry, the importance of π because of its role in circle relationships, and the role of e in applications such as continuously compounded interest.
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Isosceles Right Triangles
If a right triangle is isosceles, then it has 2 ___________ _________ and 2 ___________ __________. This means the measure of each acute angle must be ______. Thus another way to refer to Isosceles Right Triangles is as ___________ right triangles.
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45 - 45 - 90 Right Triangles
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The triangle below is an isosceles right triangle. What is the length of the hypotenuse? Calculate your answer 2 different ways.
6
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If one leg of an isosceles right triangle measures 15 feet, what is the perimeter of the triangle?
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What is the perimeter of the square?
8 2
In an isosceles right triangle, the hypotenuse is 12. What is the length of one (1) of the sides?
A.
B.
C.
D.
E.
26
62
42
32
3
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The largest triangle is equilateral
and the segment in the interior
is perpendicular to the base.
Determine the values of
x and y.
10
x
y
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30 -60 - 90 Right Triangles
When we cut an equilateral triangle with one altitude, we form 2 congruent right triangles each with one 30 and one 60 degree angle.
These are called 30 - 60 - 90 right triangles.
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30 - 60 - 90 Right Triangle Theorem
If the shortest leg of a 30-60-90 right triangle is x units long, then the hypotenuse is 2x units long and the longer leg is x times the square root of 3 units long.
30 – 60 – 90 Triangle
60°
30°
x
2xx√3
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Solve for x and y
60
18
xy
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Solve for x and y
60°
y
x24
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Solve for x and y
60°
y
34.64 x
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An altitude of an equilateral triangle is 8.3 meters. Find the perimeter of the triangle to the nearest tenth of a meter.
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Assignment
Pages 409 - 410,# 11 - 21 (odds), 33