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Kyler Carlson

Math help Please

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Kyler Carlson

I really am not having luck searching google so i think i'll ask you cuys. Whats the formula to fin the angle that 3 points make... like say i have point A, B, and C somewhere on my desktop... how can i determine the angles of them? thanks in advance.

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Paulie

I really am not having luck searching google so i think i'll ask you cuys. Whats the formula to fin the angle that 3 points make... like say i have point A, B, and C somewhere on my desktop... how can i determine the angles of them? thanks in advance.

Whipped up this UDF, i think it works... but its been a while since i tried trig..

Uses the '_Distance' UDF from SolidSnake

Func _Angle($xa, $ya, $xb, $yb, $xc, $yc, $angle = "B")
    $SideA = _Distance($xc, $yc, $xb, $yb)
    $SideC = _Distance($xa, $ya, $xb, $yb)
    $SideB = _Distance($xc, $yc, $xb, $yb)
    Switch $angle
        Case "B"
            Return ACos(($SideA^2 + $SideC^2 - $SideB^2)/(2*$SideA*$SideC))
        Case "A"
            Return ACos(($SideB^2 + $SideC^2 - $SideA^2)/(2*$SideB*$SideC))
        Case "C"
            Return ACos(($SideA^2 + $SideB^2 - $SideC^2)/(2*$SideA*$SideB))
    EndSwitch
EndFunc

Func _Distance($iX1, $iY1, $iX2, $iY2)
    Return Sqrt(($iX1 - $iX2) ^ 2 + ($iY1 - $iY2) ^ 2)
EndFunc

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cppman

not sure how to do it code-wise, but if its a right angle, pothagorean's theorum... remember a triangle has 180 degrees total... otherwise...

idk so gl lol

I Thought the pythogorean theorum was for finding the length of the hypotenuse?

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4gotn1

Pythagorean Theorem

http://www.cut-the-knot.org/pythagoras/index.shtml

Let's build up squares on the sides of a right triangle. Pythagoras' Theorem then claims that the sum of (the areas of) two small squares equals (the area of) the big one.

In algebraic terms, a2 + b2 = c2 where c is the hypotenuse while a and b are the legs of the triangle.

:whistle: so yea a simple check to make sure its a true triangle would be

If  $SideA + $SideB + $SideC <> "180"  Then  Exit
MsgBox(0, "Error", "Their was an error in the calculation")
Edited by 4gotn1

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jinxter

wasn't $sideA $SideB and $SideC distances ? it's the angles that should be 180.

if no angle in the triangle is 90 degrees you can't use pythagoras theorem.


> there are 10 types of people in the world, those who understand binary and those who don't.

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jvanegmond

I hope you like Trigonometry , but it's not very hard.

What you are looking for in particul is the law of cosines.

a^2 = b^2 + c^2 - 2.b.c.cos(alpha)
b^2 = a^2 + c^2 - 2.a.c.cos(beta)
c^2 = a^2 + b^2 - 2.a.b.cos(gamma)
Edited by Manadar

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