McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
3. Special Right Triangles
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Exercise 40 Page 646

Start with recalling the properties of special right triangles.

Variable Value
x 6
y 10
z 6sqrt(3)

Perimeter: 38+6sqrt(2)+6sqrt(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.

Now let's take a look at the given picture. We will name the missing vertices.

First of all, we can see that SR and TU are congruent as SRTU is a rectangle. Therefore, the value of y is also 10.

Since △ URQ is a 30^(∘)-60^(∘)-90^(∘) triangle, the length of the hypotenuse is 2 times the length of the shorter leg. RQ= 2RU 12=2( x) x=6 The value of x is 6. We can add this information to our picture.

Next, let's recall that in a 30^(∘)-60^(∘)-90^(∘) triangle the length of the longer leg is sqrt(3) times the length of the shorter leg. UQ=RU* sqrt(3) z= 6sqrt(3) The value of z is 6sqrt(3).

Let's notice that ST and RU are congruent. Therefore, the length of ST is 6. As we can see, △ PST is a 45^(∘)-45^(∘)-90^(∘) triangle, so the length of PT is also 6 and the length of PS is 6sqrt(2).

Finally, as we found all side lengths of trapezoid PQRS, we can evaluate its perimeter, P. P=PS+SR+RQ+PQ P=6sqrt(2)+10+12+(6+10+6sqrt(3)) P=38+6sqrt(2)+6sqrt(3) The perimeter of trapezoid PQRS is 38+6sqrt(2)+6sqrt(3).