When you create equation driven curves, the values you use must be in radians.
You cannot use global variables directly for equation driven curves. However, you can create a global variable and associate it with a dimension, then use the dimension in the equation for the curve.
Additional information:
 To control the curve rotation, you can drag the curve, add relations, and so on. The curve acts as any other rigid curve or block.
 To scale the curve, you need to account for scaling in the equation. For instance, in the example below, you can multiply X and Y by 10.
 To set start and end coordinates, for parametric curves, the start and end points are initially the evaluation of X and Y at T1 and T2. You can transform the curve by adding relations or dimensioning the start and end points to other sketches or model geometry.
Example of explicit equation:
 y_{x} = sqrt( 4  x ^ 2)
 x_{1} = 2
 x_{2} = 2


Example of parametric equation:
 x_{t} = 50*cos(t)
 y_{t} = 50*sin(t)
 t_{1} = 0
 t_{2} = pi


Example of 3D equation driven curve:
 x_{t} = 2*sin(t)
 y_{t} = 2*cos(t)
 z_{t} = t
 t_{1} = 0
 t_{2} = 30

