[RESOLVED] arccos problems?

[j0e2]

Hello..

I'm already knew there is no ArcCos or ArcSin in Visul Basic..

after searching on internet i've got this code..

Public Function Arccos(X) As Double
   If Round(X, 8) = 1# Then Arccos = 0#: Exit Function
   If Round(X, 8) = -1# Then Arccos = PI: Exit Function
   Arccos = Atn(-X / Sqr(-X * X + 1)) + 2 * Atn(1)
End Function

unfortunately, i dont know why the answer was wrong..

i try on calculator cos-1 (-0.7071) = 134.999

but when i use the code above, the result give me = 1.583137

PS: already use some kind like convert radiant to degree or reversal .. (*PI/180)

any help?

[Philly0494]

Math.Acos(.5)

will return the arc cosine of .5

Asin and Atan also work for arc sines and arc tangents

[j0e2]

sorry.. but it seems.. math.Acos / math.Asin was not arc cosinus (cos-1) or arc sinus (sin-1) on visual basic...

the result math.Acos(-0.7071) = 2.35619

[Philly0494]

yeah, 2.35619 is the answer in Radian form, you want it in degrees just convert it like this

Math.Acos(.5)*180.0 / Math.PI

[j0e2]

wow..greatz..
i think converting to radiant-degree just like this

math.Acos(.5*180/PI)

THX philly..