10 questions · Form 3 Mathematics Bab 7: Plans and Elevations
If a cylinder with radius 3 cm and height 8 cm is viewed from the side, what shape is its side elevation?
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. If a cylinder with radius 3 cm and height 8 cm is viewed from the side, what shape is its side elevation?
Answer: B
The side view of a cylinder projected onto a vertical plane is a rectangle with width equal to the diameter (6 cm) and height 8 cm.
2. What is an orthogonal projection?
Answer: B
An orthogonal projection is formed when projection rays from an object intersect the plane of projection at right angles (90°).
3. In a 4-quadrant plan and elevation layout, if the Front Elevation is drawn in Quadrant II, where is the Plan drawn?
Answer: C
In standard arrangement, the Plan is positioned in Quadrant III, directly below the Front Elevation in Quadrant II.
4. Looking from directly above a right circular cone, what shape does its Plan form?
Answer: B
The Plan of a cone viewed from top is a circle representing the base, with a point at the centre representing the apex.
5. What is the shape of the plan of a sphere with radius r?
Answer: B
The orthogonal projection of a sphere onto any plane (Plan or Elevation) is a circle of the same radius.
6. What is the orthogonal projection of a straight line segment that is parallel to the projection plane?
Answer: B
When a line is parallel to the plane of projection, its orthogonal projection is a line segment of equal length.
7. What angle is used for the construction alignment line in the standard 4-quadrant layout for drawing plans and elevations?
Answer: B
A 45° construction line in Quadrant IV is used to project horizontal dimensions between the Plan and Side Elevation.
8. A triangular prism with a right-angled triangular cross-section rests on its rectangular base. What is the shape of its Front Elevation when viewed perpendicular to the triangular face?
Answer: B
Looking directly at the triangular cross-section face gives an orthogonal projection of a triangle.
9. Why are projection lines (construction lines) drawn lightly in plans and elevations?
Answer: B
Construction lines are thin guidelines used to transfer dimensions and maintain alignment between the Plan, Front, and Side elevations.
10. If an inclined face of a prism is viewed in an orthogonal projection from above, how does its area in the Plan compare to its actual surface area?
Answer: B
An inclined (slanted) surface appears foreshortened in an orthogonal projection, making its projected area smaller than its true surface area.