# What dimensions do I need to add to this on a flashlight?

I am doing a reverse engineering project and it continues to say I need three more dimensions and I can't figure out what it is. Can someone help me figure out what they are?

I am assuming the green ellipsis are what you are trying to dimension and constrain here.

Is there a dimension or constraint that is deeping the ellipse centered? it looks like they could be moved in the Z direction as there is nothing dimensioned to the centerline. or a vertical fixed edge.

are the ellipses fixed rotationaly? if the center point is assumed to be fixed could the eclipse be rotated?

fully define a 2d sketch in autodesk inventor

I'm making an assumption here that Inventor is a little like SOLIDWORKS.
When I have an under-defined sketch, I'll exercise it.
Grab some point or line in the sketch and try to move it around the screen. You should quickly see the type of motion to constrain. After exercising, just press undo to put everything back where it was. Then you can add the required dimension(s).

Otherwise I agree with Stephen's observations.

to find missing constraints use the right mouse button and choose "Show all degrees of freedom"

I assume that you didn't fix the orientation (suggestion "horizontal" for the main axis) of the two ellipses and the height position of the left ellipse.

A couple issues regarding reverse engineering:
The b radii shown violate symmetry. You have many dimensions referencing the centers of the ellipses, however the center of something is difficult to actually measure. Instead of radii use height and width, and the other things your calipers can actually get a hold of. Then you may mirror across the centerline.
If you can’t measure referencing the round edge, you could measure the inside distance between the ellipses (not center to center) and dimension that after the mirror operation.