Question

The figure below is a net for a right rectangular prism. Its surface area is 150 ft2 andthe area of some of the faces are filled in below. Find the area of the missing faces,and the missing dimension.

Answer 1

Remember that

the surface area of the figure is equal to the sum of the areas of its faces

so

SA=2(A)+2(27)+2(36)

and

SA=150 ft2

therefore

150=2(A)+2(27)+2(36)

solve for A

150=2A+54+72

150=2A+126

2A=150-126

2A=24

A=12 ft2

Part 2

Find out the dimensions

we have that

A=L*4

A=12 ft2

so

L*4=12

L=3 ft

therefore

the dimensions are 3 ft by 4 ft