Identify the solid: which 3D form has a polygonal base and triangular lateral faces that converge and intersect at a single apex (common vertex)?

Introduction / Context:
Recognizing standard solids is essential in visualization, sectioning, and development (pattern) drawing. Each classical solid has characteristic faces, edges, and symmetries that impact how it is drawn and dimensioned.

Given Data / Assumptions:

• The base is a polygon (e.g., triangle, square, hexagon).
• The lateral faces are triangles.
• All triangular faces meet at a single vertex (apex).

Concept / Approach:

A pyramid consists of a polygonal base with triangular sides converging at an apex. The number of triangular faces equals the number of base edges. By contrast, prisms have two parallel, congruent polygonal bases with rectangular (or parallelogram) lateral faces; cones have a circular base and a curved surface; a torus is donut-shaped.

Step-by-Step Solution:

Verification / Alternative check:

Orthographic views of pyramids show characteristic taper and triangular side edges meeting at the apex; developments unfold into a fan of congruent triangles around the base polygon.

Why Other Options Are Wrong:

Prism: has two parallel equal polygonal bases and rectangular/parallelogram sides.

Cone: base is circular with a smooth curved lateral surface.

Torus: generated by revolving a circle about an axis to form a ring; no polygonal base or triangular faces.

Common Pitfalls:

Confusing a right pyramid with an oblique one; both are still pyramids if the lateral faces remain triangular and meet at a single apex.

Final Answer:

Pyramid