Hey. I’m a student and I just started learning rhino 7. I need to do a truss roof for my school course with rhino without using grasshopper. There are a lot of tutorials in internet but all of them are using grasshopper. What is the easiest way to do the whole truss roof only with rhino? Thank you in advance.
Roof trusses can have many forms - can you make a sketch of what kind of truss you would like to model?
Well, the easiest would be to draw this exactly as the image shows using lines and arcs, make a planar surface from them that looks like the black outline, then simply extrude it to the desired thickness.
That of course is not prototypically how roof trusses are made, as generally they are separate wood or metal elements (beams, struts) that are joined together. They may have different cross sections depending on where they are located in the truss. The top chord may indeed be a series of straight segments instead of an arc as shown. How the pieces are joined together may also be an important detail. So the most realistic method will be to model these individual elements separately as extrusions/polysurfaces.
I suggest you research a bit more into trusses and find some more detailed images/schematics to guide you. This is fairly basic modeling with simple lines/curves and extrusions.
Adding to what @Helvetosaur said, maybe asking the professor the intent of the project will give you a direction. Elements in a truss can be pretty funky once you start getting really granular into the structure of them. (Even before considering the actual engineering, which is way beyond my scope of work 
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