A right circular cone of base radius $R$ and vertical height $H$ rests with its flat circular base on the horizontal plane. Which of the following correctly describes its top view (plan) and front view (elevation) in first-angle orthographic projection?
Options:
(A) Top view is a circle with a central point; Front view is an isosceles triangle.
(B) Top view is an isosceles triangle; Front view is a circle.
(C) Top view is an ellipse; Front view is a rectangle.
(D) Top view is a circle; Front view is a right-angled triangle.
Answer Key:
A
Step-by-Step Solution & Explanation
**Method 1: Orthographic Projection Principles**
- Looking down vertically along the rotational axis of symmetry (top view / plan), the circular base is visible as a circle of radius $R$, with the apex appearing as a dot at the exact geometric center.
- Looking horizontally from the front (front elevation), the projected outline is an isosceles triangle of base $2R$ and height $H$.
Option **A** is correct.