What is the surface area of the triangular prism? A triangular prism. The rectangular sides are 3 feet by 6 feet, 3 feet by 7.5 feet, and 3 feet by 4.5 feet. The triangular sides have a base of 6 feet and height of 4.5 feet.

[Not drawn to scale]

54 square feet
67.5 square feet
81 square feet
85.5 square feet

20 bags of seed is needed for the new lawn

Step-by-step explanation:

To answer this question, first find the area of the lawn and divide the area calculated by the number of square feet per bag of seed.

A  lawn is assumed to have a rectangular shape, the area (A) of the lawn  therefore is

               A = L x W

Where:    A = Area of lawn

                L = Length of lawn

               W =  Width of lawn

                A = L x W

                 L = ?

                W = 60 ft

To find the length, use the formula for the perimeter of a rectangle since the lawn is assumed to a rectangular shape

Perimeter (P) = 2(L+W)

                  P = 300 ft

            300  = 2(L + 60) ft

            300  = 2L + 120

Subtract 120 from both sides

   300 - 120  = 2L + 120 - 120

              180 = 2L

Divide both sides of the equation by the coefficient of L which is 2

         180/2 = 2L/2

             90 = L

              L  =  90 ft

That is, the length of the lawn is 90 ft

To calculate the area of the lawn

              A  = L x W

              L   =  90 ft

              W  = 60 ft

               A  = 90 ft x 60 ft

               A  = 5400 square feet

This means that the area of the lawn is 5,400 square feet

To get the number of bags of seed that will cover the lawn, divide the area of the lawn by the number square feet that a bag will cover.

Number of bags of seed  = Total Area of lawn/Number square feet per bag.

Total Area                          = 5400 square feet

Number square

feet per bag                      = 270

Number of bags               = 5400/270

                                          = 20 bags of grass seed

20 bags of seed is needed for the new lawn