Question

A spiral is made up of successive semi-circles, with centres alternately at a and b starting with centre at a, of radii 0.5 cm, 1.0 cm, 1.5 cm. what is the total length of such a spiral made up of thirteen consecutive semi-circles. (take  = 22 7 )

Answer 1

We know that,
Length of semicircle = πr
l1, = π x 0.5 cm
l2 = π x 1.0 cm
3 = π x 1.5 cm
And, l4 = π x 2.0 cm and so on.
Let l be the total length of such a spiral made up of thirteen consecutive semi-circles.

Hence, total length of such a spiral made up of thirteen consecutive semi-circles = 143 cm.