What other dimensions do I need to include to fully define this sketch?

Maybe just couple construction lines and radius

Corey,

          Can you send the file, so I can look at it. I am thinking you do not need any more dimensions. But you do need some relations.

You need some symmetric relations

It's much quicker to draw one corner and construction lines, then do 2 mirrors. That way the symmetric relations are added automatically and you don't need any of the equal relationships

Hi Corey,

Drag any of the sketch segments and you will see what constraint is missing.

Temporarily fix a point. If it fully defines the sketch than you know you need to lock down any point of the sketch.

Elmar

To fully define a sketch not only do you have to have dimensions on defining the length, width , and heights of the lines/arcs, but you also have to define it's location in space in relation to the front, top, and right planes, or the origin. 

0,0,0 is the origin.  So you need dims and or relations to that point to be able to define any sketch.  Think about what you would need to be able to redraw that sketch to 100% accuracy and dimension away.

Hello,

1. I would add one radial dim to each of one of the left & right arcs:
   1. They'll be driven, but it will be an indicator to others that the central construction line terminates at their centers (and to you if they don't).
2. Symmetry is needed to keep the 120 dim central, (which is an assumption by me) since the short horizontal line equals are left/right only
   1. Coradial forces concentricity and equal radius, but not equal arc length, so if you move the 120 line up or down, the arc pairs will be different lengths and short lines on the same side won't remain equal
      One of these should cover it:
      1. Add an equal to both left short lines (or right lines, but not both sides of the sketch)
      2. 120 line midpoint horizontal to origin (only one 120 line required)

Cheers,

Kevin