Core Connections Geometry, 2013
CC
Core Connections Geometry, 2013 View details
Chapter Closure

Exercise 139 Page 334

a We have been given the angle and hypotenuse, and we want to determine the opposite leg labeled x. Given this information, we have to use the sine ratio to calculate x.
sin θ =Opposite/Hypotenuse
sin 15^(∘)=x/20
Solve for x
20sin 15^(∘) =x
x=20sin 15^(∘)
x=5.17638...
x≈ 5.176
The side labeled x is about 5.176 meters.
b We have been given the angle and opposite leg and want to determine the adjacent leg labeled x. Given this information, we have to use the tangent ratio to calculate x.
tan θ=Opposite/Adjacent
tan 15^(∘) =5/x
Solve for x
tan 15^(∘) * x=5
x=5/tan 15^(∘)
x=18.66025...
x≈ 18.66
The side labeled x is about 18.66 inches.
c We have been given the hypotenuse and adjacent leg to an unknown angle labeled θ. Given this information, we have to use the cosine ratio to calculate θ.
cos θ =Adjacent/Hypotenuse
cos θ =10/11
Solve for θ

cos^(-1)(LHS) = cos^(-1)(RHS)

θ= cos^(- 1) 10/11
θ=24.61997...
θ≈ 24.62
The angle labeled θ is about 24.62^(∘).
d Since we know both legs of the right triangle, we can use the Pythagorean Theorem to find the hypotenuse.
a^2+b^2=c^2
6^2+12^2=x^2
Solve for x
36+144=x^2
180=x^2
x^2=180
x=± sqrt(180)

x > 0

x= sqrt(180)
x=13.41640...
x≈ 13.416
The hypotenuse is about 13.416 feet
e We have been given the adjacent and opposite leg of the angle labeled x. Given this information, we have to use the tangent ratio to calculate x.
tan θ =Adjacent/Opposite
tan x =8/5
Solve for θ

tan^(-1)(LHS) = tan^(-1)(RHS)

x= tan^(- 1) 8/5
x=32.00538...
x≈ 32
The angle labeled x is about 32^(∘).
f We have been given the hypotenuse and opposite leg of the angle labeled θ. Given this information, we have to use the sine ratio to calculate x.
sin θ =Opposite/Hypotenuse
sin θ =4/5
Solve for θ

sin^(-1)(LHS) = sin^(-1)(RHS)

θ= sin^(- 1) 4/5
θ=53.13010...
θ≈ 53.1
The angle labeled θ is about 53.1^(∘).
g We have been given the hypotenuse and adjacent leg of the angle labeled y. Given this information, we have to use the cosine ratio to calculate x.
cos θ =Adjacent/Hypotenuse
cos y =9/10
Solve for y

cos^(-1)(LHS) = cos^(-1)(RHS)

y= cos^(- 1) 9/10
y=25.84193...
y≈ 25.8
The angle labeled y is about 25.8^(∘).