If six cubes of 10 cm edge are joined end to end, then the surface area (in sq. cm) of the resulting solid is
If six cubes are joined together, the new length of the cuboid formed = 60cm, breadth 10 cm and height = 10 cm. Now the surface area of cuboid formed
= 2 ( l × b ) + ( b × h ) + ( l × h ) i.e, = 2 ( 60 × 10 ) + ( 10 × 10 ) + ( 60 × 10 ) = 2 ( 1300 ) = 2600 cm²
John built a rectangular cardboard box 25 cm high with a square base and a volume of 2500 cm³. Then he realized he did not need a box that large, so he chopped off the height of the box reducing its volume to 1,000 cm³ Was the new box cubical? Also, state its’ height.
Volume of cuboid = length × breadth × height = Base area × height
Base area = 2500/25 = 100 cm² Length = √100 = 10 cm Now, 1000 = 10 ×10 = new height New height = 1000/ 10 × 10 = 10 cm Yes, the new block was cubical.
Find the surface area of a cube whose edge is 15 cm.
The edge of the cube = 15 cm, i.e., a = 15 cm. Surface area of the cube = 6a2 = 6 × (15)2 = 1350 cm2.