McGraw Hill Glencoe Geometry, 2012
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McGraw Hill Glencoe Geometry, 2012 View details
3. Special Right Triangles
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Exercise 37 Page 564

Start with recalling the properties of special right triangles.

x=9sqrt(2)
y=6sqrt(3)
z=12sqrt(3)

Practice makes perfect

Let's begin by reviewing the properties of special right triangles.

45^(∘) -45 ^(∘) -90 ^(∘) Triangle 30 ^(∘) -60 ^(∘) -90 ^(∘) Triangle
In a 45^(∘) - 45 ^(∘) - 90 ^(∘) triangle, the legs l are congruent and the hypotenuse h is sqrt(2) times the length of a leg. In a 30 ^(∘) - 60 ^(∘) - 90 ^(∘) triangle, the hypotenuse h is 2 times the length of the shorter leg s, and the longer leg l is sqrt(3) times the length of the shorter leg.

Let's name the vertices of the given figure. Then we can find x,y and z, one at a time.

Finding x

We are given that ∠ CAD has a measure of 45^(∘). Therefore, △ ACD is a 45^(∘)-45 ^(∘)-90 ^(∘) triangle.
The length of the leg is x and the length of the hypotenuse is 18. By the 45^(∘)-45 ^(∘)-90 ^(∘) Triangle Theorem, the length of the hypotenuse is sqrt(2) times the length of a leg, x. x sqrt(2) = 18 Let's solve the above equation for x.
xsqrt(2)=18
Solve for x
x=18/sqrt(2)
x*1=18/sqrt(2)*1
x*1=18/sqrt(2)*sqrt(2)/sqrt(2)
x=18/sqrt(2)*sqrt(2)/sqrt(2)
x=18sqrt(2)/sqrt(2)*sqrt(2)
x=18sqrt(2)/(sqrt(2))^2
x=18sqrt(2)/2
x=9sqrt(2)/1
x=9sqrt(2)

Finding y

We are given that ∠ ABC has a measure of 60^(∘). Therefore, △ ABC is a 30^(∘)-60^(∘)-90 ^(∘) triangle.

The length of the shorter leg is y, and the length of the longer leg is 18. By the 30^(∘)-60 ^(∘)-90 ^(∘) Triangle Theorem, the length of the longer leg is sqrt(3) times the length of a shorter leg, y. y sqrt(3) = 18 Let's solve the above equation for y.
ysqrt(3)=18
Solve for y
y=18/sqrt(3)
y*1=18/sqrt(3)*1
y*1=18/sqrt(3)*sqrt(3)/sqrt(3)
y=18/sqrt(3)*sqrt(3)/sqrt(3)
y=18sqrt(3)/sqrt(3)*sqrt(3)
y=18sqrt(3)/(sqrt(3))^2
y=18sqrt(3)/3
y=6sqrt(3)/1
y=6sqrt(3)

Finding z

Let's look at the picture for the last time.

To find the value of z, we will again use the 30^(∘)-60 ^(∘)-90 ^(∘) Triangle Theorem. According to this theorem, the length of the hypotenuse z is 2 times the length of the length of the shorter leg, 6sqrt(3). z=2( 6sqrt(3))=12sqrt(3)