A sheet of metal is initially a rectangle measuring 50 cm by 30 cm
MATHEMATICS · Multi-part · CBSE · Mathematics · Areas Related to Circles · Areas Related to Circles
Problem
A sheet of metal is initially a rectangle measuring 50 cm by 30 cm. Two circular holes, each of radius 5 cm, are punched out of the sheet. Along one of the 50 cm edges, a semicircular tab of radius 15 cm is welded externally so that its diameter lies exactly on that edge. Use π=3.14.
(i) Calculate the area of metal remaining after the holes are punched and the tab is attached.
(ii) Determine the total length of the external boundary of the final shape, excluding the circular edges of the holes.
(iii) The exposed boundary (excluding the holes) is to be painted. If 1 cm of paint covers 0.8 cm of boundary length, how many centimetres of paint are required?