Trusses as shown in the figure below are to be constructed to support the roof of a building. The truss is to have a 16-foot horizontal base (joist) that spans from one wall to the opposite wall. The vertical center strut is 4 feet long.
(a) Vertical struts are located 3 horizontal feet inside each wall. How long are these vertical struts?
b) The rafter extends 1.5 horizontal feet outside the wall. If the top of the wall is 8 feet above the floor, how high above the floor is the outside tip of the rafter?
+130536 a) 4 / 8 = L / 3 where L is the length of the strut .....cross- multiply
12 = 8L divide both sides by 8
12/8 = L = 1.5 ft
b) I can't see a picture....but........the rafter and the top of the wall form vertical angles inside and outside the structure......the rafter will be as far below the top of the wall 1.5 ft outside the wall as it is above the wall 1.5 ft inside the structure........so we have
4 / 8 = H / 1.5 where H is the height pf the rafter 1.5 from the wall on the inside of the structure.....cross-multiply
6 = 8H divide both sides by 8
3/4 ft = H
So....the rafter will be [8 - 3/4] ft = 7.25 ft from the floor at its tip on the outside of the building
