McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
2. The Pythagorean Theorem and Its Converse
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Exercise 18 Page 634

Recall the most common Pythagorean Triples and find a common factor of the known values.

x=30

Practice makes perfect

Before we begin, let's recall the definition of a Pythagorean Triple.

A Pythagorean Triple is a set of three nonzero whole numbers a, b, and c, that satisfy the equation a^2 +b^2=c^2.

Let's list some of the common Pythagorean Triples.

Common Pythagorean Triples a^2+b^2=c^2
3, 4, 5 3^2+ 4^2= 5^2
5, 12, 13 5^2+ 12^2= 13^2
8, 15, 17 8^2+ 15^2= 17^2
7, 24, 25 7^2+ 24^2= 25^2

Here we want to use a Pythagorean Triple to find the value of x in the given triangle.

To find x, we can start by finding a common factor of the given values. Notice that 78 and 72 are both multiples of 6. This means that we can rewrite them as a product of 6 and other number. Let's do it! 6 * 13= 78 6 * 12= 72 Now, since 5, 12, 13 is a Pythagorean Triple, the missing length x must also fit this pattern. Therefore, the missing length will be a product of 5 and 6. 6 * 5 = 30 We can check this by substituting these values into the Pythagorean Theorem. 30^2+ 72^2 ? = 78^2 ⇕ 6084=6084 ✓ We end up with a true statement so our solution is correct.