Deriving the atan2 Function from Tangent Half-Angle Formulas

In summary, the atan2 function is a mathematical function that calculates the arctangent of a ratio using the coordinates of a point on a plane. It is derived from tangent half-angle formulas, which allow for a more efficient and accurate calculation. The process involves expressing the tangent of an angle in terms of half the angle and considering the quadrant of the angle. Some real-world applications of the atan2 function include computer graphics, robotics, navigation systems, and various scientific and engineering calculations.
  • #1
mnb96
715
5
Hello, it is mentioned http://en.wikipedia.org/wiki/Atan2#Definition" that using the tangent half-angle formulas it is possible to express the function atan2 as:

[tex]\mathrm{atan2}(y,x)=2\mathrm{arctan}\frac{y}{\sqrt{x^2+y^2}+x}[/tex]

How can I derive this result?
 
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  • #2
Put y = rsinθ, x = rcosθ, then y/(√(x2 + y2) + x) = sinθ/(1 + cosθ),

which you should be able to prove is tan(θ/2) :wink:
 
  • #3
Thanks!
Now it´s clear where that formula came from.
 

What is the atan2 function and what does it do?

The atan2 function is a mathematical function that calculates the arctangent of the ratio of its two arguments. In other words, it determines the angle in radians between the positive x-axis of a plane and the point given by the coordinates (x,y).

What are tangent half-angle formulas and how are they related to the atan2 function?

Tangent half-angle formulas are trigonometric identities that express the tangent of an angle in terms of half the angle. They are used to derive the atan2 function, which also involves calculating the arctangent of a ratio.

Why is it important to derive the atan2 function from tangent half-angle formulas?

Deriving the atan2 function from tangent half-angle formulas allows for a more efficient and accurate way to calculate the arctangent of a ratio. This is especially useful in computer programming and scientific calculations.

What is the process of deriving the atan2 function from tangent half-angle formulas?

The first step is to use the tangent half-angle formulas to express the tangent of the angle in terms of half the angle. Then, using the inverse tangent function, the angle can be solved for. Finally, the atan2 function is derived by considering the signs of the coordinates in relation to the quadrant of the angle.

What are some real-world applications of the atan2 function?

The atan2 function is commonly used in computer graphics, robotics, and navigation systems. It can also be used in physics and engineering calculations involving angles and ratios. Additionally, the atan2 function is used in various programming languages to calculate the angle between two points on a coordinate plane.

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