Question

What is the perimeter of the given shape if a thread of 6 cm can cover the curved edge perfectly?

Answer 1

Since the given shape is symmetrical about the given line as shown in the below figure.



Length of other straight edge will also be 4 cm.

The thread is able to cover the curve edge perfectly so the length of the curve edge is 6 cm.

So the perimeter if the given shape will be equal to sum of all the edges.

Perimeter = Length of 3 straight edges + Length of 1 curve edges.

= 4 cm + 4 cm + 5 cm + 6 cm
= 19 cm