Passage:
The adjoining figure shows 3 stairs, where L = 85 cm, B = 45 cm and H = 30 cm.
Based on this information choose the correct option for the question.
The perimeter of the side view is
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 450 cm
The side view is the staircase outline. Its three treads together are as long as the bottom edge (3B), and its three risers together are as tall as the back edge (3H), so the outline is as long as the perimeter of a 3B by 3H rectangle.
Horizontal edges: bottom \(135\) cm, treads \(45+45+45=135\) cm
Vertical edges: back \(90\) cm, risers \(30+30+30=90\) cm
Perimeter \(=135+135+90+90=450\) cm
Tip: A staircase outline always has the same perimeter as the rectangle round it, because the steps only move the horizontal and vertical pieces, never shorten them.