Find C with the Pythagorean Theorem

c = √(a² + b²)

Use this find c Pythagorean theorem calculator guide to square the legs, add them, and take the square root.

In the formula a² + b² = c², c is the hypotenuse: the side opposite the right angle and the longest side of the triangle.

1Find c step by step

Write the formula

Start with c² = a² + b².

c² = a² + b²

Square the legs

Calculate a² and b² using the known side lengths.

c² = 9 + 16

Add them

Sum the squares to get c².

c² = 25

Square root

Take √ to solve for c.

c = 5

For a right triangle with legs 3 and 4, the calculator uses the same c = √(a² + b²) workflow.

Known sides

Use the two legs as the known inputs.

a = 3, b = 4

Formula

Square both legs and add the results to get c².

c² = 9 + 16

Answer

The square root gives the hypotenuse length.

c = √25 = 5

The hypotenuse is c. It is the side opposite the 90° angle.

You need the two legs, a and b. Enter both values and the calculator finds c with c = √(a² + b²).

No. c is the hypotenuse, so it is always the longest side of a right triangle.

Review the core formula and calculator phrases for right triangle problems.

Walk through classic substitutions, squaring, and square-root steps.

Turn ladders, diagonals, layouts, and distance stories into calculator inputs.

Need a quick answer? Use the calculator.