WASSCE SHS
A section shows the inside as if the object were cut. A development is the surface laid flat, at its true size.
A cutting plane is the imaginary cut. Its line on the drawing shows where the cut is taken and which way you look. The sectional view shows the solid that the plane actually cuts, hatched with thin lines at 45 degrees, evenly spaced. Adjacent parts are hatched in opposite directions so you can tell them apart. A shaft, a bolt, a nut, a rib or a web is left unhatched when the cutting plane passes along its length. That is the usual convention: a thin part cut along its length would look solid and confuse the reading. Hidden lines are normally left off a sectional view, because the cut has already shown the inside.
A development is the true shape of a surface opened out flat, so a sheet can be cut and folded to make the object. A right cylinder opens into a rectangle. The width of the rectangle is the circumference of the base, and the height is the height of the cylinder. A right cone opens into a sector of a circle. The radius of that sector is the slant height of the cone, and the arc length is the circumference of the base. A square prism opens into a row of equal rectangles for the sides, plus the top and the bottom. Do not hatch a development. Hatching belongs to the section, not to the flat pattern.
The Technical Drawing tips guide sets out the objective paper, the geometry paper including vector geometry, and the drawing paper. Start practising on glearn.now with Kevin and Anna. WASSCE Technical Drawing tips
Hatching is at 45 degrees and it stays inside the material that was cut. Empty holes are not hatched. Opposite directions separate adjacent parts. A development is true size, so a cylinder is a rectangle whose width is the circumference, not a sketch of the tube. The cone is a sector, not a triangle, unless you also say it is the sector of the unrolled surface. Name the cutting plane before you describe the section.
These are practice questions in the style of the paper, with a model answer and a mark scheme. They are not a promise of what your paper will ask.
2 marks
State two rules for hatching a sectional view. (2 marks)
Hatch the cut material with thin lines at 45 degrees. Hatch adjacent parts in opposite directions. Do not hatch a hole, and do not hatch a shaft or a rib cut along its length.
3 marks
Describe the development of a right cylinder. (3 marks)
The development is a rectangle. Its width is the circumference of the base. Its height is the height of the cylinder.
2 marks
What is the development of a right cone, and what length is the radius of that shape? (2 marks)
A sector of a circle. The radius of the sector is the slant height of the cone.
More questions on this topic are inside glearn, marked as you answer, with the reason written out. The first ones need no account.
Practise Technical Drawing freeNo. A bolt, a shaft, a nut, a rib or a web cut along its length is left unhatched. Hatching is for the material the cutting plane cuts across. Holes are left blank.
A rectangle. The width is the circumference of the base and the height is the height of the cylinder. A cone develops as a sector whose radius is the slant height. Do not hatch a development. All WASSCE Technical Drawing past questions