Question

Construct a square whose perimeter is 20 cm.

Answer 1

Given: Perimeter P = 20 cm; the figure to construct is a square all four sides equal.

Step-wise calculation:

1. For a square, P = 4 × side.

2. Side = `P/4`

= `20/4`

= 5 cm

3. Construction (straightedge and compass; follow the standard method for “construct a square when a side is given”):

Draw segment PQ = 5 cm.

At P construct a 90° ray (PM) and at Q construct a 90° ray (QN) on the same side of PQ.

On PM mark point S so that PS = 5 cm. On QN mark point R so that QR = 5 cm.

Join S and R to complete square PQRS.

The constructed square PQRS has side 5 cm and perimeter 4 × 5 = 20 cm, as required.