If we want to calculate area of a circle, We can use the value of pi like this pi = acos(-1.) . How does the inverse function work here and how it gives the value of pi here? Thanks in advance.

asked 15 Jul '16, 16:10

shuddha7435's gravatar image


acos() is just a function which calculates cos^-1(x), where x is an angle.

We have, cos(180) = -1 (the angle is in degree unit)

Now, if we convert the angle from degree to radians, we get,

cos(180* (pi/180)) = -1 (we have, 1 degree = pi/180 radians)

or, cos(pi) = -1

therefore, pi = cos^-1(-1)

which can be expressed in C as: acos(-1)

Note that, acos() is just a built in function in C under the header file math.h just like sin(), cos(), tan() or sqrt(), abs() etc.

permanent link

answered 18 Jul '16, 06:55

Najat's gravatar image


Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text](http://url.com/ "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 15 Jul '16, 16:10

question was seen: 976 times

last updated: 18 Jul '16, 06:55