勾股定理计算器

Q: What is the Pythagorean theorem?

The Pythagorean theorem states that in a right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides: a² + b² = c². It lets you find any missing side when you know the other two.

Q: How do I find the hypotenuse?

Use c = √(a² + b²). Square both legs, add the results, then take the square root. For example, if a = 6 and b = 8: c = √(36 + 64) = √100 = 10.

Q: Can I use this for non-right triangles?

No, the Pythagorean theorem only applies to right triangles (triangles with a 90° angle). For non-right triangles, use the Law of Cosines: c² = a² + b² − 2ab·cos(C).

Q: What are Pythagorean triples?

Pythagorean triples are sets of three positive integers that satisfy a² + b² = c². Common examples include (3, 4, 5), (5, 12, 13), (8, 15, 17), and (7, 24, 25).

Q: How do I know which side is the hypotenuse?

The hypotenuse is always the longest side and is always opposite the right angle (90°). In the formula a² + b² = c², c is always the hypotenuse.

解直角三角形。输入两条已知边，求第三边、面积和周长。

什么是勾股定理计算器？

The Pythagorean theorem is one of the most fundamental and widely used results in all of mathematics. It states that in any right-angled 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.

This calculator lets you solve a right triangle in three ways: find the hypotenuse when you know both legs, find one leg when you know the other leg and the hypotenuse, or verify whether three given sides form a valid right triangle. Every result includes the area, perimeter, and a complete step-by-step derivation so you can follow the algebra.

公式

Pythagorean Theorem: a² + b² = c²

Finding the hypotenuse: c = √(a² + b²)

Finding leg a: a = √(c² - b²)

Finding leg b: b = √(c² - a²)

Area: A = ½ab

Perimeter: P = a + b + c

如何计算

Choose what you want to find: the hypotenuse or one of the legs.
Enter the two known side lengths.
The calculator applies the Pythagorean theorem and shows the full algebraic derivation.
Review the area and perimeter of the right triangle.

示例

For a right triangle with legs a = 3 and b = 4: c = √(3² + 4²) = √(9 + 16) = √25 = 5. Area = ½ × 3 × 4 = 6 square units. Perimeter = 3 + 4 + 5 = 12 units.

主要优势

Three solving modes: find hypotenuse, find leg a, or find leg b
Animated SVG right triangle visualization with labeled sides
Full step-by-step algebraic derivation using KaTeX-rendered formulas
Instant area and perimeter calculation
Copy, share, and export results with one click

需要避免的常见错误

Applying the theorem to non-right triangles — it only works for 90° angles
Confusing which side is the hypotenuse — it is always the longest side, opposite the right angle
Subtracting when you should add (or vice versa) — remember: c² = a² + b² to find c, but a² = c² − b² to find a leg
Forgetting to take the square root after adding or subtracting the squares

专业提示

Use Pythagorean triples (3-4-5, 5-12-13, 8-15-17) to quickly check your work
The hypotenuse is always the longest side of a right triangle
If a² + b² > c², the triangle is acute; if a² + b² < c², it is obtuse
For coordinate geometry, the distance between two points is just the hypotenuse of a right triangle formed by the horizontal and vertical differences

关键术语解释

斜边: The longest side of a right triangle, opposite the right angle
直角边: Either of the two shorter sides of a right triangle that form the right angle
勾股数: Three positive integers a, b, c that satisfy a² + b² = c²
直角三角形: A triangle with exactly one 90° angle
平方根: The inverse operation of squaring a number

常见用例

Solving geometry homework and exam problems
Construction — calculating diagonal distances
Navigation — finding straight-line distances between two points
Architecture — verifying right angles in building layouts
Physics — resolving vector components

常见问题

What is the Pythagorean theorem?

The Pythagorean theorem states that in a right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides: a² + b² = c². It lets you find any missing side when you know the other two.

How do I find the hypotenuse?

Use c = √(a² + b²). Square both legs, add the results, then take the square root. For example, if a = 6 and b = 8: c = √(36 + 64) = √100 = 10.

Can I use this for non-right triangles?

No, the Pythagorean theorem only applies to right triangles (triangles with a 90° angle). For non-right triangles, use the Law of Cosines: c² = a² + b² − 2ab·cos(C).

What are Pythagorean triples?

Pythagorean triples are sets of three positive integers that satisfy a² + b² = c². Common examples include (3, 4, 5), (5, 12, 13), (8, 15, 17), and (7, 24, 25).

How do I know which side is the hypotenuse?

The hypotenuse is always the longest side and is always opposite the right angle (90°). In the formula a² + b² = c², c is always the hypotenuse.

勾股定理计算器

什么是勾股定理计算器？

公式

如何计算

示例

主要优势

需要避免的常见错误

专业提示

关键术语解释

常见用例

常见问题

相关工具

勾股定理计算器

什么是勾股定理计算器？

公式

如何计算

示例

主要优势

需要避免的常见错误

专业提示

关键术语解释

常见用例

常见问题

相关工具