What is the ACOS function in Excel?
The ACOS function is one of the math functions of Excel.
It returns the arccosine of a number, in radians in the range 0 to Pi.
The arccosine is the angle whose cosine is the Number.
The domain of arccosine is the interval [−1,1] and it’s undefined elsewhere.
We can find this function in Math&trig of insert function Tab.
How to use ACOS function in excel
- Click on an empty cell (like F5).

2. Click on the fx icon (or press shift+F3).

3. In the insert function tab you will see all functions.

4. Select math and trig category.
5. Select ACOS function.
6. Then select ok.

7. In the function arguments Tab you will see ACOS function.
8. Number field is the cosine of the angle you want and must be from -1 to +1.
9. You will see the result in the formula result section ( ACOS (1)=0).

Examples of ACOS function in excel
Example 1:
How to use ACOS function in excel
You can see examples of ACOS function below:

acos(-1) ----->>>>answer is 3.141
acos(-0.5) ----->>>>answer is 2.094
acos(0) ----->>>>answer is 1.570
acos(0.5) ----->>>>answer is 1.047
acos(1) ----->>>>answer is 0
math.acos(a).
How to plot Y=ACOS(X) with python code in excel
we can use Python code for acos function in excel:
import math
import numpy as np
import matplotlib.pyplot as plt
x =np.linspace(–1,+1, 100)
lenx=len(x)
y=[]
for i in range(lenx):
y.append(math.acos(x[i]))
i +=1
plt.plot(x,y)
plt.show()
What is the purpose of ACOS function?
It returns the arccosine of a number, in radians in the range 0 to Pi. The arccosine is the angle whose cosine is the Number.
What is the Return value of ACOS function?
It returns a number.
How many arguments does ACOS function have?
This function has just 1 Argument.
The argument of ACOS function is number.
Number field is the cosine of the angle you want and must be from -1 to +1.
The argument of ACOS function is required and not optional.
ACOS(number) = number
Which version of excel supports ACOS function?
This function is available for all excel versions (2003-2019).