This is a Visual Basic program that can plot the path of a projectile, the basic concept of missile launching.
This path is determined by the launching angle and
speed. The formula is y=(Vsin a) t- 1/2(gt^{2}) and x=(Vcosa)t, where
V=launching speed and a is the launching angle, g is acceleration due to
gravity(9.8n ms^{-2}) while t is time.

In this program, we use a picture box for drawing the curve . The command **Pset** is used to plot the
curve. Pset is a method that draw a point on the screen. Using loop such as the do loop will connect all the points into a line.

Private Sub cmd_Draw_Click()

Dim x, y, v, t, a As Single

v = Txt_Speed.Text

a = Txt_Angle.Text

Pic_Curve.Cls

Do

t = t + 0.01

y = v * Sin(a * 3.141592654 / 180) * t - 4.9 * (t ^ 2)

x = v * Cos(a * 3.141592654 / 180) * t

Pic_Curve.PSet (x, 120 - y)

If x > 120 Then

Exit Do

End If

Loop

End Sub

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