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Cos 0

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Last updated date: 25th Apr 2024
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Cos 0 Degree Value

Cos 0 equals to 1 (Cos 0 = 1). In other words, the value of Cos 0 is 1. Now, the question is how the value of Cos 0 has been derived. The value can be determined through the usage of quadrants of a unit circle. The process is discussed in the following section.


As you already know, trigonometric functions refer to angular functions that relate to the angles of a triangle. For studying periodic phenomena of light and sound waves, trigonometric functions have been used. These functions are also crucial for studying harmonic oscillation and average temperature variations.

Formula to find Cos

The cosine function of an angle follows a particular formula. According to this formula, the value of a cosine function of an angle is the length of the adjacent side divided by the length of the hypotenuse side. The formula is written below.


Cos X = \[\frac{\text{Adjacent Side}}{\text{Hypotenuse Side}}\]


This formula talks about the cosine (cos) function and how to determine its value. Let us take the example of a right-angled triangle that has one of its acute angles defined as x. Then the cosine formula cos x = (adjacent side) / (hypotenuse), where the adjacent side to the angle x is as the name mentions, and the hypotenuse side is the longest (the one that is opposite to the right angle in a triangle). Apart from this general formula, there are other specific formulas as well but this one is also sufficient for students to get a good understanding of how the value of cos is calculated.

Why are Trigonometric Functions Important?

In Mathematics, they are essential for a few things such as complex analysis and Fourier analysis. Alternatively, they will be universal as solutions, examples, tricks, and many exercises in every field of Maths including differential equations, geometry, topology, Hilbert spaces, etc.


If we talk about physics and engineering, these functions are something to be found everywhere. Whenever something is circular, whenever something reoccurs itself in time, you can expect to see sin and cos given in its description. That also includes sound waves, electromagnetic waves (including light), any type of wave, how particles behave, and so on.


Aside from being used in fundamental theory and theoretical modeling, these functions have a purpose of building blocks and motivation in secondary uses such as helping students in expanding their knowledge and aiding in development. Not only are these easy to remember but also very fun to solve and play with as students. 

How to find the Value of Cos 0?

There are three basic trignometric ratios, and they are sine function, cosine function, and tangent function. With the help of the sin, cos, and tan functions, the angles of a triangle can be calculated.


For understanding the cosine function of an acute angle, you need to draw a right-angled triangle on a piece of paper. The triangle obviously has three sides, and these sides can be defined in the following way: Choose an angle of the triangle, and the opposite side of the chosen angle will be called the “opposite side”. The side of the triangle placed opposite to the right angle has been called the “hypotenuse side”. Notably, this is the longest side of a right-angle triangle. Finally, the “adjacent side” refers to the remaining side of the triangle.  Determining Value of Cos 0 with Unit Circle Using a unit circle, the “Cos 0” value can be derived. The process starts with assuming a unit circle that shares its center with the origin of the coordinate axes.

Why is the Value of Cos Always Less Than or Equal to 1?

The very easy way to understand the reason is that the length measurement of the sides of a right triangle is at all times less than the length measurement of the hypotenuse angle. So, the proportion of any side and hypotenuse is also at all times less than the value 1.

What is Cos 0?

The value of the cosine in the 0° right triangle is known as the cosine of angle 0°. The cosine of angle 0° is a value, which denotes the remainder of the length of the adjacent side to the length of hypotenuse if the angle of a right triangle is equivalent to 0°.


Under the Sexagesimal system, the cos of zero degrees angle is mathematically expressed as cos 0° and the exact value of the cosine of angle 0° = 1 . Thus, mathematically it is written in the following form in trigonometry i.e cos 0° = 1


We can also express the cosine of angle zero degrees in two other forms under trigonometric Mathematics ie. circular system and centesimal system.

Cos 0 in  Circular System

In a circular system, the cosine of zero degrees is mathematically represented as the cosine of zero radians. It is written in the following form in circular system cos (0) =1. It is noted that in a unit circle method the one whole revolution subtends an angle of 2π radian at the very center of the unit circle, as all the angles of a triangle are the much-needed multiples of π/2 and it is frequently known as quadrantal angles in academics. Consequently, the coordinates of the points on the triangle become (1, 0), (0, 1), (–1, 0), and (0, –1) respectively. Therefore, using the quadrantal angles, we can easily derive the values of Cos.

Cos 0 in  Centesimal System

Similarly, In a centesimal system, the cosine of zero degrees is mathematically represented as the cosine of zero degree grades. It is written in the following form in the centesimal system cos (0^9) =1. In this system, one of the right angles is divided into 100 identical parts that are known as grades. It is also known as the French system of measurement. Each of the grades is then divided into 100 identical parts called minutes and each of the minutes is then divided into 100 identical parts known as the seconds. Thus, 1 right angle is equal to 100 grades (1009), 1 grade is equal to 100 minutes (100') and 1 minute is equal to 100 seconds (100")

Basic Understanding to define Cos 0 as 1

The value of Cos 0 degree:

To have a better understanding of the cosine function concerning an acute angle, start with considering a right-angled triangle, with the angle that interests you and the sides of a triangle. All the sides(three) of the triangle are defined as under:

  • The opposite side is known as the side opposite the angle of interest.

  • The hypotenuse side is the one that is on the opposite of the right angle and it is the longest side in the triangle.

  • The remaining side is called the adjacent side and that is where it forms a side of together the angle of interest along with the right angle.

How to keep These Values in Mind?

To have such a tough task of memorizing a lot of values or simply some random numbers of the trigonometric functions seems to be a high-grade punishment at first with no academic purpose or benefit. Some people use the table to memorize the values, some use the circular unit to do to at 0 degrees, the angle is studied according to the Unit Circle at the coordinates (1,0). These coordinates are nothing else but trigonometric values. The x-coordinate is the value relating to cos and the y-coordinate is the value relating to sin. 


Yet understanding the working of the formula is the best way. This was you will not be mugging up numbers and forgetting later on and also have a thorough understanding of the value of Cos 0, why is it 1, and much more.

FAQs on Cos 0

1. What is the Value of Cos 0?

 Cos 0° is equal to \[\sqrt \frac {4}{4}\]  =1. The standard angles such as cos 0°, 30°, 45°, 60° and 90° are all possibly the positive roots of their fractional values.

2. How can we remember Cos Value?

Here is a quick trick to remember the values of the cos 0 degrees. Just remember cos goes in a reverse direction like "3,2,1". That being said, the value for various degrees of cos goes like this:

cos(30°) = \[\sqrt \frac {3}{2}\],

cos(45°) = \[\sqrt \frac {2}{2}\],

cos(60°) = \[\sqrt \frac {1}{2}\],

cos 90° = \[\sqrt \frac {0}{4}\] = 0

Now that we are aware of the sin and cos value of the standard angles, thus we are easily able to find the values of the other trigonometric ratios of the standard angles.

3. What is a Trigonometric Table and its importance?

The Trigonometrical ratios table will significantly enable you to identify the values of trigonometric standard angles of various trigonometric ratios such as O°, 30°, 45°, 60° and 90°.


The values of trigonometric ratios of standard angles play a significant role when it comes to solving trigonometric problems. Hence, it becomes essential for the students to remember the value of these standard angles of the trigonometric ratios.

4. What is the value of Cosine of the standard angles?

First, you need to remember to not get confused between cos and cosine. Both are different trigonometric angles. Thus, find below the standard angles of cosine 0°, 30°, 45°, 60° and 90° which are:

  • csc 0 degrees = not defined. 

  • csc 30 degrees = 2

  • csc 45 degrees = \[\sqrt {2}\]

  • csc 60 degrees = \[\sqrt \frac {23}{3}\]

  • csc 90 degrees = 1.

5. What do Trigonometry Functions refer to?

Trigonometric functions refer to angular functions that relate to the angles of a triangle. Sin, Cos, and Tan are the functions of which values need to be defined.