a rectangular solid of metal 42 em by 30 cm by 20 em, a conicalcavity

1.	a rectangular solid of metal 42 em by 30 cm by 20 em, a conicalcavity of base radius 14 cm and height 20 cm is drilled out. Find thesurface area of remaining solid.iin the form of a cylinder of base radius12 m
Answer» Total surface area of cuboid = 2(ℓb + bh + ℓh) = 2 (42 × 30 + 30 × 20 + 20 × 42) = 2 (1260 + 600 + 840) = 2 × 2700 = 5400 cm2 Diameter of the cone = 14 cm Radius of the cone =14/2 = 7cm Surface area of remaining part = 5400 + 550 – 154 = 5796 cm2

a rectangular solid of metal 42 em by 30 cm by 20 em, a conicalcavity of base radius 14 cm and height 20 cm is drilled out. Find thesurface area of remaining solid.iin the form of a cylinder of base radius12 m

Answer»

Total surface area of cuboid = 2(ℓb + bh + ℓh)

= 2 (42 × 30 + 30 × 20 + 20 × 42)

= 2 (1260 + 600 + 840)

= 2 × 2700

= 5400 cm2

Diameter of the cone = 14 cm

Radius of the cone =14/2 = 7cm

Surface area of remaining part = 5400 + 550 – 154 = 5796 cm2