Step by Step Exercise
Setting up the drawing: Drawing Limits, Zoom All
How big is your site or object? Always consider the real sizes in metres (or mm or whatever) of the overall site, in plan, measuring width then height. (x,y dimensions).
This house is small, we will be thinking in metres, so it should fit into an area of 15mx12m
Pick: Format, Drawing Limits
Accept the lower-left limit < 0.0000, 0.0000 > (Press Enter ¿ ) then type in 15,12¿ to define a new upper-right limit
Pick: View, Zoom, All to stretch to the new limits this has provided you with a drawing area suitable to your project, but it will not stop you extending beyond this area later
Check your status line. POLAR and OSNAP should be active

From the drop-down menus
Pick: Draw, Arc, Start-End-Angle
Pick: point to the endpoint of the line to begin the arc.
Type @4<90 ¿ (4 units straight up)
Move the mouse until a full semicircle is displayed, then click again.
Pick: Line and snap to the Endpoint of the arc.
Complete the figure.
Offset the eaves (also useful for the leaves of a cavity wall)

Download pdf 3D Modelling in AutoCAD - Tutorial Exercise