# How to Calculate a Right Triangle: A Step-by-Step Guide

A right triangle, also known as a right-angled triangle, is a triangle in which one angle measures exactly 90 degrees. These triangles are fundamental in various branches of mathematics, including geometry and trigonometry. In this guide, we’ll walk you through the steps to calculate the sides and angles of a right triangle, whether you have some or all of the side lengths or angle measurements.

**1. Understand the basic properties of right triangles:**

Before diving into calculations, it’s essential to understand the core properties of a right triangle:

– One angle measures exactly 90 degrees (the right angle)

– The side opposite the right angle is known as the hypotenuse. This side will always be the longest side of the triangle.

– The other two sides are called legs.

**2. Familiarize yourself with Pythagorean theorem:**

The Pythagorean theorem is fundamental for calculating sides in a right triangle. This theorem states that in a right triangle, the sum of the squares of lengths of both legs equals the square of the hypotenuse length (a² + b² = c²), where ‘a’ and ‘b’ represent leg lengths and ‘c’ represents the hypotenuse length.

**3. Calculate missing side lengths:**

If you have two side lengths, you can use the Pythagorean theorem to find the remaining side length:

a) If given both leg lengths (a and b), you can calculate the hypotenuse (c):

c = √(a² + b²)

b) If given one leg length (a or b) and hypotenuse length (c), you can calculate the other leg length:

a = √(c² – b²) or b = √(c² – a²)

**4. Learn about trigonometric ratios for calculating angles:**

With these three ratios, you can find the missing angles in a right triangle:

– Sine (sin) = Opposite side / Hypotenuse

– Cosine (cos) = Adjacent side / Hypotenuse

– Tangent (tan) = Opposite side / Adjacent side

**5. Calculate angles using inverse trigonometric functions:**

If you have all three side lengths of a right triangle, you can use inverse trigonometric functions to calculate the other two angles. Since the sum of all angles in a triangle equals 180 degrees, and one angle in a right triangle is 90 degrees, the other two angles add up to 90 degrees.

a) Use arcsine (sin⁻¹) to find angle A:

Angle A = sin⁻¹(opposite side / hypotenuse)

b) Use arccosine (cos⁻¹) to find angle B:

Angle B = cos⁻¹(adjacent side / hypotenuse)

**6. Remember the complementary rule for right triangles:**

Since two unknown angles add up to 90 degrees, once you find one angle, you can easily determine the other by subtracting it from 90 degrees.

Now you know how to calculate both sides and angles in a right triangle using Pythagorean theorem, trigonometric ratios, and inverse trigonometric functions. Don’t forget to practice—that’s the key to mastering this skill!