Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
2. Special Right Triangles
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Exercise 24 Page 504

Divide the given triangle into two right triangles. Do you have a 30^(∘)-60^(∘)-90^(∘) or a 45^(∘)-45^(∘)-90^(∘) triangle?

a=6, b=6sqrt(2), c=2sqrt(3), and d=6

Practice makes perfect

Let's divide the given triangle into two right triangles.

We will deal with these triangles one at a time.

Triangle 1

Notice that this is a right triangle with an acute angle that measures 60^(∘). Therefore, by the Triangle Angle Sum Theorem the measure of the third angle must be 30^(∘).
We have a 30^(∘)-60^(∘)-90^(∘) triangle. In this type of triangle, the length of the hypotenuse is twice the length of the shorter leg.
4sqrt(3) = 2 * c
Solve for c
2sqrt(3) = c
c = 2sqrt(3)
We found that the length of the shorter leg is 2sqrt(3). Moreover, in a 30^(∘)-60^(∘)-90^(∘) triangle the length of the longer leg is sqrt(3) times the length of the shorter leg. This will let us find the value of a.
a=sqrt(3) * 2sqrt(3)
Simplify right-hand side
a=2sqrt(3)sqrt(3)
a=2(sqrt(3))^2
a=2(3)
a=6

Triangle 2

Our second right triangle has an angle that measures 45^(∘). Therefore, by the Triangle Angle Sum Theorem the measure of the third angle is also 45^(∘). Remember, we already know that a=6.

This triangle is a 45^(∘)-45^(∘)-90^(∘) triangle. In this type of triangle, both legs are congruent and the length of the hypotenuse is sqrt(2) times the length of a leg. With this information, we can find the values of b and d. d & = 6 b &= sqrt(2) * 6 = 6sqrt(2)