Right Triangles Calculator

Input Values

Enter any two known values to calculate the remaining properties of the right triangle.

units
units
units
°
°

Results

Side a
-
Side b
-
Side c
-
Angle A
-
Angle B
-
Angle C
90°
Area (K)
-
Perimeter (P)
-

Altitudes

Altitude Value Description
Altitude ha - Altitude to side a
Altitude hb - Altitude to side b
Altitude hc - Altitude to hypotenuse c

Right Triangle Diagram

Right triangle with angles A, B, C and sides a, b, c a b c A B C (90°) hc

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Triangle: Right

A = angle A
a = side a
B = angle B
b = side b
C = angle C
c = side c

K = area
P = perimeter

See Diagram Below:
ha = altitude of a
hb = altitude of b
hc = altitude of c

triangle-right-altitude

Right Triangles Calculator

Right Triangles Calculator is an essential geometry tool that helps you find missing sides, angles, perimeter, and area of a right triangle using simple formulas derived from the Pythagorean Theorem. Whether you’re solving homework problems or handling construction layouts, this calculator makes trigonometry fast, precise, and effortless.

A right triangle has one 90° angle. The relationship between its sides is expressed by the Pythagorean Theorem, written as:
a² + b² = c²,
where a and b are the legs, and c is the hypotenuse (the longest side opposite the right angle).

🔹 What Is a Right Triangle?

A right triangle is a triangle with one right (90°) angle. It’s the foundation for trigonometry and appears in architecture, physics, and engineering. Its unique property allows you to calculate unknown sides or angles when you know any two elements — sides or angles.

For example, if you know sides a and b, you can easily find c (the hypotenuse):
c = √(a² + b²)

Once all sides are known, you can determine:

  • Perimeter (P) = a + b + c
  • Semiperimeter (s) = (a + b + c) / 2
  • Area (K) = (a × b) / 2
  • Altitudes:
    • ha = b
    • hb = a
    • hc = (a × b) / c

🧮 How to Use the Right Triangles Calculator

This calculator computes all missing triangle properties instantly when you input any two known sides or angles.

You can solve in two main scenarios:

1. When sides a and b are known:

  • c = √(a² + b²)
  • P = a + b + c
  • s = (a + b + c) / 2
  • K = (a × b) / 2
  • ha = b
  • hb = a
  • hc = (a × b) / c

2. When sides a and c are known:

  • b = √(c² – a²)
  • P = a + b + c
  • s = (a + b + c) / 2
  • K = (a × b) / 2
  • ha = b
  • hb = a
  • hc = (a × b) / c

These formulas make it easy to find missing sides, area, and perimeter without any manual calculations.

📏 Understanding Right Triangle Components

To master the Right Triangles Calculator, it helps to know the meaning of each element:

SymbolDescriptionFormula
aBase (one leg)Given or computed
bHeight (other leg)Given or computed
cHypotenuse√(a² + b²)
PPerimetera + b + c
sSemiperimeter(a + b + c) / 2
KArea(a × b) / 2
haAltitude from ab
hbAltitude from ba
hcAltitude from c(a × b) / c

Each value is interconnected, so once you know two sides, the rest can be found effortlessly.

📚 Related Concepts and Calculators

Understanding right triangles opens the door to exploring other triangle types and theorems:

These tools build your understanding of geometric relationships and improve problem-solving in real-world applications.

🔹 Finding Angles in a Right Triangle

Apart from sides, angles are crucial. In a right triangle:

  • One angle is 90°.
  • The other two are acute angles that add up to 90°.

You can find these using basic trigonometric ratios:

  • sin(θ) = opposite / hypotenuse
  • cos(θ) = adjacent / hypotenuse
  • tan(θ) = opposite / adjacent

If you know one side and one angle (besides the right angle), you can calculate the remaining sides using:

a = c × sin(θ)
b = c × cos(θ)

These are the same equations that power the Triangle Angle Calculator, ideal for exploring non-right triangle cases.

⚡ Why Use a Right Triangle Calculator?

Using the Right Triangles Calculator eliminates manual errors and saves time. It’s especially useful for:

  • Students solving geometry or trigonometry problems
  • Architects and engineers measuring dimensions
  • DIY enthusiasts planning structures or layouts

Key benefits include:

  • Instant and precise results
  • Easy-to-understand output
  • Ability to handle feet, inches, or metric units
  • Compatibility with different triangle types

The Right Triangle Calculator (feet and inches) mode is particularly helpful for construction or carpentry where mixed measurements are common.

🔸 Difference Between Right, Equilateral, Isosceles & Obtuse Triangles

To deepen your geometric understanding, compare right triangles with other types:

TypeDescriptionKey Formula
Right TriangleOne 90° anglea² + b² = c²
Equilateral TriangleAll sides equalArea = (√3 / 4) × a²
Isosceles TriangleTwo sides equalArea = (b / 4) × √(4a² – b²)
Obtuse TriangleOne angle > 90°Use Law of Cosines

For detailed explorations, you can also use tools like the Isosceles Triangle Calculator or the Obtuse Triangle Calculator for non-right-angled cases.

🧠 Example: Finding the Missing Side

Suppose a = 6 cm and b = 8 cm.
Then,
c = √(6² + 8²) = √(36 + 64) = √100 = 10 cm

Now:

  • P = 6 + 8 + 10 = 24 cm
  • s = 12 cm
  • K = (6 × 8) / 2 = 24 cm²
  • hc = (6 × 8) / 10 = 4.8 cm

With just two inputs, you’ve found all seven triangle parameters — exactly what the Right Triangles Calculator automates in seconds.

🧩 Practical Applications

Right triangles appear everywhere — from navigation systems to physics. Engineers use them to measure slopes, electricians calculate cable lengths, and designers determine layout proportions.

You can further extend this knowledge by exploring the Distance Between Two Points Calculator on CalculatorCave, which applies similar geometric logic to coordinate geometry.

The Right Triangles Calculator is your go-to tool for finding missing sides, angles, and area with ease. By understanding the underlying Pythagorean Theorem and basic trigonometry, you’ll grasp how every triangle measurement connects.

Whether you’re calculating in feet, inches, or centimeters, or comparing with other triangle types like isosceles or equilateral, this calculator ensures accuracy and clarity every time.

Geometry becomes intuitive once you see how every number fits together — and this calculator is the key that unlocks that understanding.