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 23 Page 504

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

a=7, b=14, c=7, d=7sqrt(3)

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 45^(∘). Therefore, by the Triangle Angle Sum Theorem the measure of the third angle must also be 45^(∘).
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 a and c.
7sqrt(2)=sqrt(2) * a
7=a
a=7
Because, the legs in this type of triangle are congruent, the value of variable c is also 7.

Triangle 2

Our second right triangle has an angle that measures 30^(∘). Therefore, by the Triangle Angle Sum Theorem the measure of the third angle is 60^(∘). Remember, we already know that a=7.

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. b= 2 * 7 ⇔ b=14 We found that the length of the hypotenuse is 14. 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 d. d=sqrt(3) * 7 ⇔ d=7sqrt(3)