Specify the length of an edge I want to create an equilateral triangle. 

I added a plan and then merged the two points on one edge .. that seemed to work fine. 

The length of the bottom of the triangle is 2m and I'd like to set the length of the other edges to 2m. 

Is there an easy way to set the length of an edge?

I understand that I can do some math and figure out the x,y for the top and move that point to create the correct length, but I'd like to just set the length of an edge if possible.
Further to comments, to create an equilateral triangle, side length L -


ShiftA call up a Circle
In the fields of the Adjust Last Operation panel, type into Sides: 3,  and Radius: L*sqrt(3)/3