Special Right Triangles Calculator

The Special Right Triangles Calculator solves 45-45-90 and 30-60-90 triangles with mathematical precision. Specially developed for students, teachers and professionals working with geometry, offering complete calculations including sides, angles, perimeter and area. Supports input by individual sides, perimeter or area, providing instant results with graphic visualization of the triangle and detailed explanations of geometric properties.

Updated at: 06/03/2025

How the Special Right Triangles Calculator Works

The Special Right Triangles Calculator is a versatile tool designed to solve two unique types of right triangles: the 30°-60°-90° triangle and the 45°-45°-90° triangle. By inputting the length of one side, the calculator instantly computes the remaining sides, perimeter, and area, providing a comprehensive solution for these specific triangle types.

This calculator leverages the fixed side ratios inherent to these triangles—1:√3:2 for the 30°-60°-90° triangle and 1:1:√2 for the 45°-45°-90° triangle. These consistent ratios allow for straightforward calculations, making the tool invaluable for students, educators, and professionals in fields like geometry, engineering, and architecture.

Understanding Special Right Triangles

Special right triangles are right-angled triangles with angles and side ratios that follow specific, consistent patterns. The two most common types are:

  • 30°-60°-90° Triangle: This triangle has angles measuring 30°, 60°, and 90°. The sides are in the ratio 1:√3:2, meaning the length of the sides opposite these angles follow this proportion.

  • 45°-45°-90° Triangle: This is an isosceles right triangle with two 45° angles and one 90° angle. The sides are in the ratio 1:1:√2, indicating the legs are equal in length, and the hypotenuse is √2 times the length of a leg.

These triangles are frequently encountered in geometry due to their predictable ratios, which simplify calculations and problem-solving.

Fundamental Formulas

For a 30°-60°-90° Triangle:

  • Short Leg (opposite 30°):

  • Long Leg (opposite 60°):

  • Hypotenuse (opposite 90°):

  • Area:

  • Perimeter:

For a 45°-45°-90° Triangle:

  • Legs (both equal):

  • Hypotenuse:

  • Area:

  • Perimeter:

These formulas allow for efficient calculations of a triangle's dimensions and properties when one side length is known.

Detailed Examples

Example 1: 30°-60°-90° Triangle with Short Leg = 5

  • Long Leg:

  • Hypotenuse:

  • Area:

  • Perimeter:

Example 2: 45°-45°-90° Triangle with Leg = 7

  • Hypotenuse:

  • Area:

  • Perimeter:

These examples illustrate how knowing a single side length enables the determination of all other properties of these special right triangles.

What Is the Perimeter of a 30°-60°-90° Triangle?

The perimeter of a 30°-60°-90° triangle can be calculated using the formula:

Where is the length of the short leg. This formula simplifies the process of finding the perimeter when the short leg is known.

How to Find the Area of a 45°-45°-90° Triangle?

To find the area of a 45°-45°-90° triangle, use the formula: