The Equation Driven Curve tool lets you create a curve by defining the equation for that curve.
Select an existing equation driven curve or create a new one (for example, by clicking Equation Driven Curve tool (Sketch toolbar) or .
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.
Existing Relations
If you select an existing curve:

Displays relations inferenced automatically during sketching or created manually with Add Relations. When you select a relation in the list, a callout is highlighted in the graphics.


Displays the status of the selected sketch entity (Fully Defined, Under Defined, and so on). 
Add Relations
If you select an existing curve, you can add relations to the selected entity. The list includes only relations that are possible for the selected entity.
Options
If you select an existing curve, click For construction to convert the entity to construction geometry.
Equation Type
Explicit 
Lets you define X values for the start and endpoints of the range. Y values are calculated along the range of X values. 
Parametric 
Lets you define T values for the start and endpoints of the range. You can define an equation for X values and another equation for Y values. Both equations are solved along the range of T values. Only parametric curves are available in 3D sketches.

Parameters
You can specify any appropriate combination of the following parameters to define the curve if the curve is not constrained by relations.
Equation 
(explicit equations) 
Define the curve equation, where Y is a function of X. Or, define the curve equation, where X, Y, and Z are functions of T. Z is for 3D sketches only. If you type an equation that cannot be solved or has incorrect syntax, the equation appears in red.
You can use any functions supported in the Equations dialog box. For example, you can build complex equations like this: 2*(x + 3*sin(x))
You can also use feature dimensions in equations. For example:
x^3/"D1@Sketch5"

, , and (parametric equations) 
Parameters 
and (explicit equations) 
Specify the range of values for _{1}, where _{1} is the starting point and _{2} is the ending point (for example, X_{1} = 0 and X_{2} = 2*pi).Click to lock or unlock the start or end point location on the curve:
 (locked): The starting or ending point is fixed.
 (unlocked): You can drag the starting or ending point along the curve.

and (parametric equations) 