Table of Contents

Welcome to **cos pi**, our post aboutthe cosine of pi.

For the cosine of pi we use the abbreviation *cos* for the trigonometric function and write it as cos pi.

If you have been looking for *what is cos pi*, or if you have been wondering about cos pi radians in degrees, then you are right here, too.

In this post you can find the cos pi value, along with identities.

Read on to learn all about the cos of pi.

## Cos Pi Radians

If you want to know *what is cos pi radians* in terms of trigonometry, then navigate straight to the explanations in the next paragraph; what’s ahead in this section is the value of cos pi:

cos pi = -1

cos pi radians = -1

The cos of pi radians is -1, the same as cos of pi radians in degrees. To change pi radians to degrees multiply pi by by 180° / $\pi$ = 180°. Cos pi = cos 180 degrees.

Our results of cospi have been rounded to five decimal places. If you want cosine pi with higher accuracy, then use the calculator below; our tool displays ten decimal places.

To calculate cos pi radians insert the angle pi in decimal notation, but if you want to calculate cos pi in degrees, then you have to press the swap unit button first.

### Calculate cos [radians]

The identities of cosine pi are as follows:

= sin (pi/2 + pi) = sin 3/2 pi

= sin (pi/2 – pi) = sin -1/2 pi

-cospi

= cos (pi + pi) = cos 2 pi

= cos (pi – pi) = cos 0

*n*× 2pi) = cos pi, n$\hspace{5px} \in \hspace{5px} \mathbb{Z}$.

There are more formulas for the double angle (2 × pi), half angle ((pi/2)) as well as the sum, difference and products of two angles such as pi and β.

You can locate all of them in the respective article found in the header menu. To find everything about cos -pi click the link. And here is all about sin pi, including, for instance, a converter.

In terms of the other five trigonometric functions, cos of pi =

- $\pm \sqrt{1-\sin^{2} \pi }$
- $\pm\frac{1}{\sqrt{1 + \tan^{2} \pi}}$
- $\pm\frac{\cot \pi}{\sqrt{1 + \cot^{2} \pi}}$
- $\frac{1}{\sec \pi}$
- $\pm\frac{\sqrt{\csc^{2} (\pi) – 1} }{\csc \pi}$

As the cosine function is the reciprocal of the secant function, 1 / sec pi = cospi.

In the next part we discuss the trigonometric significance of cospi, and there you can also learn what the search calculations form in the sidebar is used for.

## What is cos Pi?

In a circle with the radius r, the horizontal axis x, and the vertical axis y, pi is the angle formed by the two sides x and r; r moving counterclockwise is the positive angle.

As detailed in the unit-circle definition on our homepage, assumed r = 1, in the intersection of the point (x,y) and the circle, x = cos pi.

Note that you can locate many terms including the cosinepi value using the search form. On mobile devices you can find it by scrolling down. Enter, for instance, value of cospi.

Along the same lines, using the aforementioned form, can you look up terms such as cos pi value, cos pi, cospi value and *what is the cos of pi radians*, just to name a few.

Given the periodic property of cosine of pi, to determine the cosine of an angle > 2pi, e.g. 5 pi, calculate cos 5 pi as cos (5 pi mod 2pi) = cosine of pi, or look it up with our form.

## Conclusion

The frequently asked questions in the context include *what is cos pi radians* and *what is the cos of pi degrees* for example; reading our content they are no-brainers.

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