Почему не правильно вычисляет Visual?

[Людмила_И]

код

вычислить и вывести полярные координаты по формулам


Imports System.Math
Public Class л_2
'Функция ввода координаты точки в TextBox
Function Vvod(ByVal T As TextBox) As Single
Return CSng(Val(T.Text))
End Function

'Процедура вывода результата в TextBox
Sub Vivod(ByVal Z As Single, ByVal T As TextBox)
T.Text = CStr(Z)
End Sub

'Функция вычисления полярных координат 3-х точек
Function PolK(ByVal x As Single, ByVal y As Single)
Dim R As Single
R = Sqrt(x ^ 2 + y ^ 2)
Return R
End Function
Function PolK1(ByVal x As Single, ByVal y As Single)
Dim Yg As Single
Yg = Atan(y / x)
Return Yg

End Function
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim x1 As Single, y1 As Single, x2 As Single, y2 As Single, x3 As Single, y3 As Single
Dim R1, R2, R3 As Single
x1 = Vvod(TextBox1)
y1 = Vvod(TextBox2)
x2 = Vvod(TextBox3)
y2 = Vvod(TextBox4)
x3 = Vvod(TextBox5)
y3 = Vvod(TextBox6)

R1 = PolK(x1, y1)
R2 = PolK(x2, y2)
R1 = PolK(x3, y3)

Vivod(R1, TextBox8)
Vivod(R2, TextBox7)
Vivod(R3, TextBox9)



End Sub

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
л_3.Show()
Hide()
End Sub

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
Close()
Form1.Show()
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim x1 As Single, y1 As Single, x2 As Single, y2 As Single, x3 As Single, y3 As Single
Dim Yg1, Yg2, Yg3 As Single
x1 = Vvod(TextBox1)
y1 = Vvod(TextBox2)
x2 = Vvod(TextBox3)
y2 = Vvod(TextBox4)
x3 = Vvod(TextBox5)
y3 = Vvod(TextBox6)
Yg1 = PolK1(x1, y1)
Yg2 = PolK1(x2, y2)
Yg3 = PolK1(x3, y3)
Vivod(Yg1, TextBox11)
Vivod(Yg2, TextBox10)
Vivod(Yg3, TextBox12)
End Sub
End Class