Hi all, I’m not sure how to draw a line with a set length (eg. 5cm). Most of the tutorials online draw random lines with no definite length and I was wondering how to do it because in sketchup, you could type the length of the line and then draw it!
Also, is there a “guideline” function for rhino? 
Hi -
After you have place the start point, just type the length of the line. If you want to use document units, you just type 5. If you are in a document with, e.g., mm as units, you could write 5cm to draw a 5 cm line.
Read about the AddGuide command in the help file.
If I type in “5” is this for the x axis or the y? Do I need to define it?
Also is there a way to determine the start point of the line?
Hello - you can click in the viewport or type in points by their x,y,z cplane coordinates directly and world coordinates by pre-pending “w”
Line
0,0,0
10,0,5
But once the start is placed, typing a single number plus Enter constrains the length of the line but not its endpoint location - that is essentially constrained only to a sphere of radius line length until you specify an end point or direction.
https://docs.mcneel.com/rhino/6/help/en-us/index.htm#user_interface/accurate_modeling.htm?
-Pascal