Download Geometry Unit 7 Notes Packet

Geometry Unit 7 Notes
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7.1 Apply the Pythagorean Theorem
7.2 Use the Converse of the
Pythagorean Theorem
7.3 Use Similar Right Triangles
7.4 Special Right Triangles
7.5 Apply the Tangent Ratio
7.6 Apply the Sine and Cosine Ratios
7.7 Solve Right Triangles
7.1:
Theorem 7.1: Pythagorean Theorem: In a right triangle, the square of the length of the
hypotenuse is equal to the sum of the squares of the lengths of the legs.
Find the length of the hypotenuse of the right triangle:
A 16 foot ladder rests against the side of a house, and the base of the ladder is 4 feet away.
Approximately how high above the ground is the top of the ladder?
Find the area of the isosceles triangle with following side lengths:
a. 10 meters, 13 meters, and 13 meters.
b. 30 feet, 18 feet, and 18 feet.
c. 20 meters, 26 meters, and 26 meters.
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Pythagorean Triples:
A Pythagorean triple is a set of three positive integers, a, b, and c that satisfy the equation
c2 = a2 + b2.
3,4,5
5,12,13
8,15,17
7,24,25
Find the length of the hypotenuse of the right triangle with side lengths of 24 and 10.
Find the unknown side length of each triangle:
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7.2:
Theorem 7.2: Converse of the Pythagorean Theorem: If the square of the length of the
longest side of a triangle is equal to the sum of the squares of the lengths of the other two
sides, then the triangle is a right triangle.
Tell whether the given triangle is a right triangle:
Tell whether a triangle with the given side lengths is a right triangle:
a. 4,4 3 ,8
b. 10, 11, 14
c. 5,6, 61
Theorem 7.3: If the square of the length of the longest side of a triangle is less than the sum
of the squares of the lengths of the other two sides, then the triangle is an acute triangle.
Theorem 7.4: If the square of the length of the longest side of a triangle is greater than the
sum of the squares of the lengths of the other two sides, then the triangle is an obtuse
triangle.
Can segments with lengths of 4.3 feet, 5.2 feet, and 6.1 feet form a triangle? If so, would the
triangle be acute, right, or obtuse?
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7.3:
Theorem 7.5: If the altitude is drawn to the hypotenuse of a right triangle, then the two
triangles formed are similar to the original triangle and to each other.
The diagram below shows a cross-section of a swimming pool. What is the maximum depth
of the pool?
Identify the similar triangles. Then find the value of x.
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Proportions involving Geometric Means in
Right triangle ABC:
BD CD

CD AD
AB CB

CB DB
AB AC

AC AD
Find the value of y. Write your answer
in simplest radical form.
Theorem 7.6: Geometric Mean (Altitude) Theorem: In a right triangle, the altitude from the
right angle to the hypotenuse divides the hypotenuse into two segments.
The length of the altitude is the geometric mean of the lengths of the two segments.
Theorem 7.7: Geometric Mean (Leg) Theorem: In a right triangle, the altitude from the right
angle to the hypotenuse divides the hypotenuse into two segments.
The length of each leg of the right triangle is the geometric mean of the lengths of the
hypotenuse and the segment of the hypotenuse that is adjacent to the leg.
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7.4:
Theorem 7.8: 45-45-90 Triangle Theorem: In a 45-45-90 triangle, the hypotenuse is
as long as each leg.
Hypotenuse = leg  2 .
Find the length of the hypotenuse:
Find the value of the variable:
6
2 times
Theorem 7.9: 30-60-90 Triangle Theorem: In a 30-60-90 triangle, the hypotenuse is twice as
long as the shorter leg, and the longer leg is 3 times as long as the shorter leg.
Hypotenuse = 2  shorter leg
Longer leg = shorter leg  3
The logo on a recycling bin resembles an equilateral triangle with side lengths of 6 cm. What
is the approximate height of the logo?
Find the values of x and y. Write your answer in simplest radical form.
The body of a dump truck is raised to empty a load of sand. How high is the 14 foot body
from the frame when it is tipped upward at the given angle?
a. 45 degree angle
b. 60 degree angle
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7.5:
A ________________________ ratio is a ratio of the lengths of two sides in a right triangle.
The ratio of the lengths of the legs in a right triangle is constant for a given angle measure.
This ratio is called the _______________ of the angle.
Tan A =
Find tan S and tan R. Write each answer as a fraction and as a decimal rounded to four
places.
Find tan J and tan K. Round to four decimal places.
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Find the value of x:
A roller coaster makes an angle of 52 degrees with the ground. The horizontal distance from
the crest of the hill to the bottom of the hill is about 121 feet. Find the height, h, of the roller
coaster to the nearest foot.
A surveyor is standing 118 feet from the base of the Washington Monument. The surveyor
measures the angle between the ground and the top of the monument to be 78 degrees. Find
the height, h, of the Washington Monument to the nearest foot.
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7.6:
The _________ and ____________ ratios are trigonometric ratios for acute angles that
involve the lengths of a leg and the hypotenuse of a right triangle.
sin A =
cos A =
Find sin S, sin R, cos S, and cos R.
Find cos U, cos W, sin U, sin W.
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Angles: If you look up at an object, the angle your line of sight makes with a horizontal line is
called the angle of ____________________. If you look down at an object, the angle your
line of sight makes with a horizontal line is called the angle of _____________________.
You are skiing on a mountain with an altitude of 1200 meters. The angle of depression is 21
degrees. About how far do you ski down the mountain?
You want to build a skateboard ramp with a length of 14 feet and an angle of elevation of 26
degrees. You need to find the height and the length of the base of the ramp.
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7.7:
To solve a right triangle means to find the measures of all of its sides and angles. You can
solve a right triangle if you know either of the following:


__________ side lengths
__________ side length and the measure of one ____________ angle
Inverse Trigonometric Ratios:
Inverse Tangent: If tan A = x, then tan-1 x = m<A
Inverse Sine: If sin A = y, then sin-1 y = m<A
Inverse Cosine: If cos A = z, then cos-1 z = m<A
Use a calculator to approximate the measure of <A and <B to the nearest tenth of a degree:
Let <A and <B be acute angles in a right triangle. Use a calculator to approximate the
measure of <A and <B to the nearest tenth of a degree:
a. sin A = 0.87
b. cos B = 0.15
c. sin D = 0.54
Solve the right triangle. Round your answer to the nearest
tenth if necessary.
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