Solution:-
The string length is the perimeter of the shape.
∴ For each case, perimeter=30cm
(i) Square
A square has all the side equal.
Perimeter=4×(side of square)
∴side of square=perimeter4=304=7.5cm
Hence, length of each side if the string is used to form a square will be 7.5 cm.
(ii) Equilateral triangle
An equilateral triangle has three equal sides.
Perimeter=3×(side)
∴side=perimeter3=303=10cm
Hence, length of each side if the string is used to form an equilateral triangle will be 10 cm.
(iii) Regular hexagon
A regular hexagon has six equal sides.
Perimeter=6×(side)
∴side=perimeter6=306=5cm
Hence, length of each side if the string is used to form a regular hexagon will be 5 cm.