Question

the sum of the surface area of a cube and area of a rectangle is 2820 cm2. if the length and breath of rectangle is 40% more and 25% less than the side of cube find the perimeter of rectangle. ​

Answer 1

Answer:

Let the side of the cube be a.

Length of rectangle = a + (40% of a) = 1.4a

Breadth of rectangle = a - (25% of a) = 0.75a

Surface Area of cube + Area of rectangle =

6a^2 + 1.4a*0.75a = 6a^2 + 1.05a^2 = 7.05a^2

7.05a^2 = 2820

a^2 = 2820/7.05 = 400

a = 20cm

Perimeter of the rectangle = 2(1.4a + 0.75a) =

2.8a + 1.5a = 4.2a = 4.2*20 = 84cm