How to extrude this

I want to extrude circle(R10) and i have dimension of "upper" one(R6)(ending of extruded object if you understand me) i dont have taper angle.I have no clue how to do that all i can do is try with different angles and thats not precious.

Try to draw half of vertical section of desired shape (frustum of a cone) and revolve it.

Regards,

Or the Cone command, specifying both the bottom and the top radius.

AutoCAD 2010 I see. I recommend the use of the LOFT command. You don't have to know the angle. The two circles can be on the same centerline or one of them can be offset and it will still work.

Re: calculate angle.

You know the radius of both circles. You must have some idea whether or not they are on the same centerline. Let's assume they are. You must also know the distance between the two circles. Let's assume it is 24. Set your angle precision in the Units dialog box to four places (use decimal angle).

In Autocad draw a horizontal line 10 units long. At one end of that line draw a vertical line 24 units long. At the end of this line draw another horizontal line (in same direction as first) 6 units long. Finally, draw a diagonal line between the end of the bottom line and the top line. Using either the List command or Properties obtain the angle of the line. That's your taper angle.

In this example that angle is 99.4623.