Table of Contents
Welcome to cos 399°, our post aboutthe cosine of 399 degrees.
For the cosine of 399 degrees we use the abbreviation cos for the trigonometric function together with the degree symbol °, and write it as cos 399°.
If you have been looking for what is cos 399°, or if you have been wondering about cos 399 degrees in radians, then you are right here, too.
In this post you can find the cos 399° value, along with identities.
Read on to learn all about the cos of 399°.
Cos 399 Degrees
If you want to know what is cos 399 degrees 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 399°:
cos 399° = 0.77715
cos 399 degrees = 0.77715
The cos of 399 degrees is 0.77715, the same as cos of 399 degrees in radians. To obtain 399 degrees in radian multiply 399° by $\pi$ / 180° = 133/60 $\pi$. Cos 399degrees = cos (133/60 × $\pi)$.
Our results of cos399° have been rounded to five decimal places. If you want cosine 399° with higher accuracy, then use the calculator below; our tool displays ten decimal places.
To calculate cos 399 degrees insert the angle 399 in the field labelled °, but if you want to calculate cos 399 in radians, then you have to press the swap unit button first.
Calculate cos [degrees]
The identities of cosine 399° are as follows:
= sin (90°+399°) = sin 489°
= sin (90°-399°) = sin -309°
-cos399°
= cos (180°+399°) = cos 579°
= cos (180°-399°) = cos -219°
There are more formulas for the double angle (2 × 399°), half angle ((399/2)°) as well as the sum, difference and products of two angles such as 399° and β.
You can locate all of them in the respective article found in the header menu. To find everything about cos -399° click the link. And here is all about sin 399°, including, for instance, a converter.
In terms of the other five trigonometric functions, cos of 399° =
- $\pm \sqrt{1-\sin^{2} 399 ^\circ}$
- $\pm\frac{1}{\sqrt{1 + \tan^{2} 399^\circ}}$
- $\pm\frac{\cot 399^\circ}{\sqrt{1 + \cot^{2} 399^\circ}}$
- $\frac{1}{\sec 399^\circ}$
- $\pm\frac{\sqrt{\csc^{2} 399^\circ – 1} }{\csc 399^\circ}$
As the cosine function is the reciprocal of the secant function, 1 / sec 399° = cos399°.
In the next part we discuss the trigonometric significance of cos399°, and there you can also learn what the search calculations form in the sidebar is used for.
What is cos 399°?
In a circle with the radius r, the horizontal axis x, and the vertical axis y, 399 degrees 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 399°.
Note that you can locate many terms including the cosine399° value using the search form. On mobile devices you can find it by scrolling down. Enter, for instance, value of cos399°.
Along the same lines, using the aforementioned form, can you look up terms such as cos 399° value, cos 399, cos399° value and what is the cos of 399 degrees, just to name a few.
Given the periodic property of cosine of 399°, to determine the cosine of an angle > 360°, e.g. 1119°, calculate cos 1119° as cos (1119 Mod 360)° = cosine of 399°, or look it up with our form.
Conclusion
The frequently asked questions in the context include what is cos 399 degrees and what is the cos of 399 degrees for example; reading our content they are no-brainers.
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– Article written by Mark, last updated on February 17th, 2017