Question

Total surface area of a cube is 5400 sq. cm. Find the surface area of all vertical faces of the cube.

Answer 1

$total \: surface \: area \: of \: a \: cube = 6 {a }^{2} \\ 5400 = 6 {a }^{2} \\ {a }^{2} = 5400 \div 6 \\ a = \sqrt{900} \\ a = 30$
so sides of cube =30cm
i.e, surface area of a cube=4(a×a)=4×30cm×30cm=3600sq.cm

Answer 2

TSA of cube = 5400

=> 6a^2 = 5400

=> a^2 = 900

=> a = 30

Side of cube = 30 cm

Surface area of each face = a^2

= 30^2

= 900 cm^2

Sum of areas of all vertical faces = 4 × a^2

= 4× 30^2

= 4 × 900

= 3600 cm^2