Page 155 - Math Course 2 (Book 1)

The Pythagorean Theorem

Mo. 5

Lesson 4

KEY CONCEPTS:
1. Use the Pythagorean Theorem to f nd the
length of the side of a right triangle.
2. Use the converse of the Pythagorean
Theorem to determine whether a triangle
is a right triangle.

Pythagorean Theorem
MO. 5 - L4a describes the relationship between the lengths of the
legs and the hypotenuse for any right triangle.
Right Triangle: Finding the

Length of the Side

Vocabulary A-Z C a

Let us learn some vocabulary
b

2
2
Legs a + b = c 2
2
In a right triangle, the sides that are adjacent to the c = a + b 2
Pythagorean theorem
right angle are called the legs. The sum of the areas of the two squares on the
legs (a and b) equals the area of the square on the
hypotenuse (c).a

Legs Solving a Right Triangle

If you know the lengths of two sides of a right
triangle, you can use the Pythagorean Theorem to
f nd the length of the third side. This is called solving
a right triangle.
Hypotenuse
c
The side opposite the right angle is the hypotenuse.
a

Hypotenuse
b
2
a + b = c 2
2
The Pythagorean theorem can be written as an
equation relating the length of the sides a, b and
c, often called the Pythagorean equation.

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