Perimeter of this shape?
A normal-level "Length" problem.However many steps there are, the answer is the same. Once you see that the area changes but the perimeter does not, this shape stops being frightening.
GivenA staircase shape. The rectangle that boxes it in is 12 cm by 9 cm
Hints
- The individual steps are not labelled — and adding them up is impossible when you cannot measure them.
- Colour only the vertical edges and slide them straight across to the right — same lengths, just moved sideways.
- Slid across, the vertical edges stack up exactly onto the rectangle's right-hand side — no gaps, no overlaps. So the verticals total 9 cm.
- The same for the horizontals: slide them down and they land exactly on the rectangle's bottom side. They total 12 cm.
- In the end the staircase's perimeter is exactly the same as the boxing rectangle's: (12 + 9) × 2. The area, of course, is smaller.
Answer 42cm
More "Length" problems
- a + b + c = ?
- What is the side of the square?
- How long is MN?
- How long is the rope?
- How long is the pole's shadow?
- How deep was the water?