How do I build a sloped roof with a 60° rake?
See the instruction for that set on pages 56-59, 65 and 68/69 for the 3 different roofs of it.

they're using a different technique and different pieces for all of them, so this perfectly shows up some alternatives (technic-like parts for the big roof to the right, blocks with studs on the sides for the small 90°-roofs and 1x1 with clips for the roof to the left).