Simplify the expression.

-1 - 6 -5r + 13r

for this case we have that by definition, the surface area of a cylinder is given by:

where:

r: it is the radius of the cylinder

h: it is the height of the cylinder

we can also rewrite it as:

where:

la: it's the lateral area

ba: area of the base

option a

the area of the piece of paper =   27- inch square.

so, the length of the square piece of paper = = .

the side of the triangle cut = =

also the side of the small square cut =

so, the area of each triangle cut = 1/2 * .

so, the area of 4 triangles cut =

area of a small square cut =

total area of 4 triangles cut and a small square cut = 6+3 = 9 square inches.

reaming area of the octagonal window   = 27 - 9 = 18 square inches.