Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
1. The Pythagorean Theorem
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Exercise 18 Page 469

Yes.

Practice makes perfect

We are given the lengths of the three sides of a triangle, and want to determine whether this triangle is a right triangle. We will need to use the Converse of the Pythagorean Theorem.

Converse of the Pythagorean Theorem

If the sides of a triangle have lengths a, b, and c, and c^2=a^2+b^2, then the triangle is a right triangle.

This tells us that we can use the Pythagorean Theorem in reverse to test if a triangle is right. In general, the hypotenuse c has the greatest value. Notice that in our exercise the greatest value is sqrt(26).

Let's substitute the side lengths of this triangle into a^2+b^2=c^2, and see if they produce a true statement.
a^2+b^2=c^2
1^2+ 5^2? =( sqrt(26))^2
1+25? =(sqrt(26))^2
1+25? =26
26=26 âś“
The values produce a true statement, so the drawn triangle is a right triangle.