Is it a Right Triangle Calculator

Verify if your triangle is a right triangle using the Pythagorean theorem and angle measurements

Check if Triangle is Right Angled

Right Triangle Check Results

⚠️ Invalid Triangle
Please enter three positive values that satisfy the triangle inequality theorem
(The sum of any two sides must be greater than the third side)

Example Calculations

Classic 3-4-5 Right Triangle

Sides: 3, 4, 5

Check: 3² + 4² = 9 + 16 = 25 = 5²

Result: ✓ Right Triangle

Right Angle: Opposite the side of length 5

Non-Right Triangle

Sides: 2, 3, 4

Check: 2² + 3² = 4 + 9 = 13 ≠ 16 = 4²

Result: ✗ Not a Right Triangle

Type: Scalene oblique triangle

Right Triangle Properties

90°

Right Angle

One interior angle equals exactly 90°

Pythagorean Theorem

a² + b² = c² (hypotenuse)

90°

Complementary Angles

Other two angles sum to 90°

Famous Right Triangles

3-4-5 Triangle

Classic Pythagorean triple

5-12-13 Triangle

Larger Pythagorean triple

45-45-90 Triangle

Isosceles right triangle

30-60-90 Triangle

Special angle triangle

Verification Tips

Square the three sides and check if a² + b² = c²

The longest side should be the hypotenuse

Check if any angle equals exactly 90°

Remember: small rounding errors are normal

Understanding Right Triangles

What is a Right Triangle?

A right triangle is a triangle with one interior angle measuring exactly 90 degrees (a right angle). This creates a special relationship between the three sides known as the Pythagorean theorem.

Key Characteristics

  • One angle is exactly 90°
  • The other two angles are complementary (sum to 90°)
  • The side opposite the right angle is the hypotenuse
  • The hypotenuse is always the longest side

Pythagorean Theorem

a² + b² = c²

  • a, b: Lengths of the two shorter sides (legs)
  • c: Length of the hypotenuse (longest side)

Verification Methods

  1. 1. Side lengths: Check if Pythagorean theorem holds
  2. 2. Angles: Verify one angle equals 90°
  3. 3. Trigonometry: Use sine, cosine, tangent ratios