Trigonometric Function. Miss understood

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Permalink Reply by alex jenter on March 12, 2013 at 9:01pm

hi Toussaint

Im sorry but my trigonometry isn't very fluent in english but by a bit of trial and error i found out that "aTan" delivers that result. By my knowlege the Arcus functions are for finding angels to known triangles? I.e. tangent(x) = y > arcangent(y) = x

am i wrong?

Permalink Reply by David Rutten on March 13, 2013 at 3:43am

ATan (ArcTangent), ACos (ArcCosine) and ASin (ArcSine) are simply the inverse functions of the Tangent, Cosine and Sine functions. Think of it as the graph of each function rotated through 90 degrees around the origin point.

 

Basically, if you want to compute the tangent of x, you need to write an equation of the form

y = tan(x)

 

If you have the tangent of an angle but want to know what angle made it, you have to use the inverse:

x = atan(y)

 

Because Sine and Cosine only go from -1 to +1 on the y-axis, you cannot use numbers outside this this range for Acos and Asin functions. After all, there exists no angle which -when cosined- results in +4

 

Note that the 'inverse' has nothing to do with 1/x in this case and the notation of sin^-1(x) to denote an arcsine is confusing and should not be used.

--

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Toussaint Jimenez Rojas on March 16, 2013 at 12:04pm

Thanks for the explanation David 

allways really helpfull 

:D

Permalink Reply by alex jenter on March 17, 2013 at 8:23am

Thanks david just went through my math book from school and it remembered me that we call those arcus functions inverse functions to in german and that my teacher told us that while the sin^-1(x) term is use widely its still misleading.  Thanks David for the memory refresh. :)