Question 100
Find the area to be painted in the following block with a cylindrical hole. Given that length is 15cm, width 12cm, height 20cm and radius of the hole 2.8cm.
Length of the given figure = 15 cm
Width of the given figure = 12 cm
Height of the given figure = 20 cm
Radius of the hole = 2.8 cm
∴ The area to be painted = Surface area of the figure - 2 × Area of the circular hole
=2(lb+bh+lh)−2πr2=2(15×12+12×20+15×20)−2×227×2.8×2.8=2(180+240+300)−44×2.8×2.87=2×720−49.28=1440−49.28=1390.72 cm2