Study Guide and Review
Find the geometric mean between each pair of numbers.
11. 9 and 4
SOLUTION: By definition, the geometric mean x of any two numbers a and b is given by
Therefore, the geometric mean of 9 and 4 is
13. and
SOLUTION: By definition, the geometric mean x of any two numbers a and b is given by
Therefore, the geometric mean of
and is
15. DANCES Mike is hanging a string of lights on his barn for a square dance. Using a book to sight the top and bottom
of the barn, he can see he is 15 feet from the barn. If his eye level is 5 feet from the ground, how tall is the barn?
SOLUTION: Draw a rough figure for the given information.
By the Geometric Mean (Altitude) Theorem the altitude drawn to the hypotenuse of a right triangle separates the
hypotenuse into two segments. The length of this altitude is the geometric mean between the lengths of these two
segments. The total height of the barn is 45 + 5 = 50 ft.
Find x.
17. eSolutions Manual - Powered by Cognero
SOLUTION: Use the Pythagorean theorem to find the missing side of the right triangle.
Page 1
Study Guide and Review
The total height of the barn is 45 + 5 = 50 ft.
Find x.
17. SOLUTION: Use the Pythagorean theorem to find the missing side of the right triangle.
Determine whether each set of numbers can be the measures of the sides of a triangle. If so, classify the
triangle as acute, obtuse, or right. Justify your answer.
19. 13, 15, 16
SOLUTION: By the Triangle Inequality Theorem, the sum of the lengths of any two sides should be greater than the length of the
third side.
Therefore, the set of numbers can be measures of a triangle.
Now, classify the triangle by comparing the square of the longest side to the sum of the squares of the other two
sides.
Therefore, by Pythagorean Inequality Theorem, a triangle with the given measures will be an acute triangle.
21. SWIMMING Alexi walks 27 meters south and 38 meters east to get around a lake. Her sister swims directly
across the lake. How many meters to the nearest tenth did Alexi’s sister save by swimming?
SOLUTION: Let x be the distance across the river.
eSolutions Manual - Powered by Cognero
Page 2
Study
Guide and
Review
Therefore,
by Pythagorean
Inequality Theorem, a triangle with the given measures will be an acute triangle.
21. SWIMMING Alexi walks 27 meters south and 38 meters east to get around a lake. Her sister swims directly
across the lake. How many meters to the nearest tenth did Alexi’s sister save by swimming?
SOLUTION: Let x be the distance across the river.
The distance saved would be the difference between the sum of the two legs of the triangle and the hypotenuse
(distance across the river). distance saved = (27+38) – 46.6 = 18.4
Alexi’s sister saved about 18.4 meters by swimming across the river. Find x and y.
22. SOLUTION: In a 30°-60°-90° triangle, the length of the hypotenuse h is 2 times the length of the shorter leg s, and the length of
the longer leg l is
times the length of the shorter leg.
Here, the length of the hypotenuse is
Then,
the shorter leg is x and the longer leg is 15. So,
.
Also we have,
23. SOLUTION: The given triangle is an isosceles right triangle, that is, 45°-45°-90° triangle. So,
In a 45°-45°-90° triangle, the legs l are congruent and the length of the hypotenuse h is
Here,
Solve for x.
eSolutions Manual - Powered by Cognero
.
times the length of a leg.
Page 3
Then,
.
Also
we have,
Study
Guide
and Review
23. SOLUTION: The given triangle is an isosceles right triangle, that is, 45°-45°-90° triangle. So,
.
In a 45°-45°-90° triangle, the legs l are congruent and the length of the hypotenuse h is
Here,
Solve for x.
times the length of a leg.
24. CLIMBING Jason is adding a climbing wall to his little brother’s swing-set. If he starts building 5 feet out from the
existing structure, and wants it to have a
angle, how long should the wall be?
SOLUTION: 10 ft. Since the ground and the side of the play structure make a
angle, this is a
is 5 feet. The climbing wall will be the hypotenuse, so it is 10 feet.
-
-
triangle. The short side
35. TOWER There is a cell phone tower in the field across from Jen’s house. If Jen walks 50 feet from the tower, and
finds the angle of elevation from her position to the top of the tower to be
, how tall is the tower?
SOLUTION: eSolutions Manual - Powered by Cognero
Page 4
10 ft. Since
the and
ground
and the side of the play structure make a
angle, this is a
Study
Guide
Review
is 5 feet. The climbing wall will be the hypotenuse, so it is 10 feet.
-
-
triangle. The short side
35. TOWER There is a cell phone tower in the field across from Jen’s house. If Jen walks 50 feet from the tower, and
finds the angle of elevation from her position to the top of the tower to be
, how tall is the tower?
SOLUTION: Let x be the height of the tower.
So, the height of the tower is 86.6 feet.
Find x. Round angle measures to the nearest degree and side measures to the nearest tenth.
37. SOLUTION: We are given the measures of two sides and their included angle, so use the Law of Cosines.
eSolutions Manual - Powered by Cognero
Page 5