The Pythagorean Theorem
Understand the relationship between the sides of a right triangle and how to use a² + b² = c² to find missing lengths.
Lesson 4 of 11
Geometry & Measurement
Concept Overview
For any right triangle, the square of the hypotenuse (the side opposite the right angle) equals the sum of the squares of the other two sides: a² + b² = c².
The Hypotenuse
The hypotenuse is always the longest side, directly opposite the 90° angle. It is represented by c in the formula.
Finding a Missing Side
To find a leg: rearrange to a² = c² − b², then take the square root. To find the hypotenuse: c = √(a² + b²).
Example
A right triangle has legs a = 3 and b = 4. Find the hypotenuse.
c = √(3² + 4²) = √(9 + 16) = √25 = 5
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Pythagorean Theorem
Solve for the missing side of a right triangle.
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