When we study the relationship of angles, heights, and lengths, it is called as Trigonometry. Trigonometry is used in almost all fields. Be it engineering, phonetics or game development, we use trigonometry for them. The values of these functions like the value of Cos 120 or Cos 0 is important in these fields.
|Value of Cos 120 is -½ .|
It has many other applications too. In some cases, it is used indirectly. For example, in creating computer music as sound travels in the form of waves. These waves follow a pattern of sine or cosine functions to develop computer music.
How to find the value of Cos 1200
As mentioned in the solution given below, 120° can be represented in terms of two angles i.e. either 90° or 180°.
We can show that 120 degrees can be represented in two angles, whose value can be taken from trigonometry table.
90 degree and 180 degree
180° – 60° = 120° ———– (1)
90° + 30° = 120° ———— (2)
Let’s use these now.
Cos 120° = cos(180° – 60°) = – cos 60° = -½ (since cos(180° – x) = – cos x)
Cos 120° = cos(90° + 30°) = – sin 30° = -½ (we know that cos (90° + x) = -sin x)
Other trigonometric ratios for different angles are:
|Trigonometry Ratio Table|
|Angles (In Degrees)||0||30||45||60||90||180||270||360|
|Angles (In Radians)||0||π/6||π/4||π/3||π/2||π||3π/2||2π|
|tan||0||1/√3||1||√3||Not Defined||0||Not Defined||0|
|cot||Not Defined||√3||1||1/√3||0||Not Defined||0||Not Defined|
|cosec||Not Defined||2||√2||2/√3||1||Not Defined||−1||Not Defined|
|sec||1||2/√3||√2||2||Not Defined||−1||Not Defined||1|
Visit BYJU’S to learn other trigonometric formulas and concepts.