Page 160 - Math Course 2 (Book 1)

Radical Expressions: Pythagorean Theorem

Mo. 5

Lesson 5 Key Concept

KEY CONCEPTS: The Pythagorean Theorem
1. Solve problems by using the Pythagorean
Theorem. Words If a and b are the lengths of the legs of a
2. Determine whether a triangle is a right right triangle and c is the length of the
triangle. hypotenuse, then the square of the
square of the length of the hypotenuse
is equal to the sum of the squares of the
lengths of the legs.
MO. 5 - L5a

Problem-Solving: c a
The Pythagorean Theorem
b

2
2
Vocabulary A-Z Symbols C = a + b 2
Let us learn some vocabulary

Let’s Begin

Legs

The other two sides of a right triangle are the legs.
Find the Length of the Hypotenuse

Example

Legs
Find the length of the hypotenuse of a right triangle
if a = 18 and b = 24.

2
2
c = a + b 2 Pythagorean Theorem
Hypotenuse
2
2
2
c = 18 + 24 a = 18 and b = 24
In a right triangle, the side opposite the right angle is 2
the hypotenuse. c = 900 Simplify.
2
This side is always the longest side of a right triangle c = + 900 Take the square root of
each side.

c = + 30 Use the positive value.
Hypotenuse

The length of the hypotenuse is
Answer
30 units.

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