3. Special Right Triangles
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In the given figure, you can find a 45^(∘)- 45 ^(∘) - 90 ^(∘) triangle.
x=5
y=10
Let's begin by reviewing the properties of special right triangles.
45^(∘) - 45 ^(∘) - 90 ^(∘) Triangle |
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In a 45^(∘) - 45 ^(∘) - 90 ^(∘) triangle, the legs l are congruent and the hypotenuse h is sqrt(2) times the length of a leg. |
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30 ^(∘) - 60 ^(∘) - 90 ^(∘) Triangle |
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. |
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We are given that ∠ BCD is a right angle, and through the process of finding y, we know that the measure of ∠ BCE is 45 ^(∘). Since ∠ DCE and ∠ BCE are complementary, the measure of ∠ DCE is also 45^(∘). Therefore, △ ECD is also a 45^(∘) - 45 ^(∘) - 90 ^(∘) triangle.
The length of the leg is x and the length of the hypotenuse is 5 sqrt(2). 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) = 5 sqrt(2) ⇔ x=5