# How to calculate degree of angle

Angles are a fundamental concept in mathematics and geometry, and understanding how to calculate the degree of an angle is an important skill. This article will walk you through the various methods you can use to calculate the degree of an angle, whether you’re dealing with right angles, straight angles, or any other types of angles.

**1. Using a Protractor**

A protractor is a simple tool that can be used to measure the degree of an angle. Follow these steps to use a protractor:

Step 1: Place the center point of the protractor on the vertex of the angle.

Step 2: Align one edge of the angle with the baseline (0-degree line) on the protractor.

Step 3: Read the degree measurement where the other edge of the angle intersects with the protractor’s scale.

**2. Trigonometric Ratios**

Trigonometry is an area of mathematics that deals with triangles and their angles. If you know certain information about a triangle, you can use trigonometric ratios such as sine, cosine, and tangent to calculate angle measurements.

For example, if you have a right triangle and know side lengths a, b (the two legs), and c (the hypotenuse), you can use these formulas:

tan(θ) = opposite / adjacent (where θ is one of the acute angles)

sin(θ) = opposite / hypotenuse

cos(θ) = adjacent / hypotenuse

From there, you can find θ by using inverse trigonometric functions like arctangent, arcsine, or arccosine.

**3. The Pythagorean Theorem**

The Pythagorean Theorem states that in any right triangle, the square of the length of its hypotenuse is equal to the sum of squares of its other two sides:

c^2 = a^2 + b^2

If you know the side lengths of a right triangle, you can use this theorem to find the measures of its acute angles using trigonometric ratios.

**4. The sum of angles in a triangle**

The sum of angles in any triangle is always equal to 180 degrees. Therefore, if you know two angles in a triangle, you can find the third angle by subtracting the sum of the known angles from 180.

**5. The Angle Addition Postulate**

The Angle Addition Postulate states that if point B lies in the interior of angle AOC, then the measure of angle AOB plus the measure of angle BOC equals the measure of angle AOC.

Using this postulate, you can determine an unknown angle by adding or subtracting known angles.

**Conclusion**

Calculating the degree of an angle can be done using various methods such as protractors, trigonometric ratios, the Pythagorean theorem, and geometry principles like the angle sum and angle addition postulates. Understanding these concepts will help you determine angle measures in various situations and mathematical problems.