Pythagoras in a keypress form

[heinousanus]

Hi. I am trying to create a form that calculates Pythagoras's Theorem, the rest of this post gets a bit complicated so I have tried to reduce the problem, to make it easier to work out. You could ignore this post and go on to the next post just below...

a squared + b squared = c squared
a^2 + b^2 = c^2.

\1

where c is the hypotenuse of a right-angled triangle (the longest side, which is directly opposite the right-angle)

and a and b are the other 2 sides (known as the adjacent and the opposite)

I have created a userform with 3 main TextBoxes known as: Adjacent, Opposite and Hypotenuse.

I want the form to work so that if someone types in values for the opposite and the adjacent sides e.g. 3 and 4, then the form will automatically calculate the hypotenuse, (in this case 5), without anyone having to click any buttons.

I can do this with this code:

Sub Calculate_Hypotenuse()

If Opposite = "" Then Opposite = 0
If Adjacent = "" Then Adjacent = 0
OppositeSquared = Opposite * Opposite
AdjacentSquared = Adjacent * Adjacent

HypotenuseSquared = OppositeSquared * 1 + AdjacentSquared * 1 'I had to put * 1 in here or else it goes doo-lally

Range("A1") = HypotenuseSquared
Range("A2").FormulaR1C1 = "=Sqrt(R[-1]C)" 'Square root the HypotenuseSquared variable to get the Hypotenuse.
Hypotenuse = Range("A2")

End Sub
Private Sub Opposite_Change()

If Opposite = "" Then Opposite = 0
Call Calculate_Hypotenuse

End Sub
Private Sub Adjacent_Change()

If Adjacent = "" Then Adjacent = 0
Call Calculate_Hypotenuse

End Sub

However, being greedy, I also want the form to automatically count the opposite side, when someone types in the adjacent and the hypotenuse. This is where it started going wrong. I tried adding this code but the computer hates it, and almost spat at me.

Private Sub Hypotenuse_Change()

If Hypotenuse = "" Then Hypotenuse = 0

HypotenuseSquared = Hypotenuse * Hypotenuse
AdjacentSquared = HypotenuseSquared - OppositeSquared

'If the HypotenuseSquared is less than the OppositeSquared then the AdjacentSquared will be a negative number, which is bad news for square roots so this next line stops that.
If AdjacentSquared < 0 Then AdjacentSquared = AdjacentSqaured * -1

Range("A2") = AdjacentSquared
Range("A1").FormulaR1C1 = "=Sqrt(R[-1]C)"
Opposite = Range("A1")

End Sub

I don't what I am doing wrong. Please help!