Question

③ in designing an iron
gril a black Smith needed 70rings with radius 7cm each
find how much length of the
A rod he required,if the wastage is
20 cm.
​

Answer 1

Circumference of one ring = 2π(7)

Then,

• Circumference of 70 rings = 70 × 2π(7)

$\sf \to \: 70 \times 2 \times \frac{22}{ \cancel7} \times \cancel7 \\ \\ \sf \to70 \times 44 \: \: \: = 3080 \: \: cm$

Given,

• Wastage = 20 cm

Thus,

• Total usage = 3080 - 20 = 3060 cm