What is the formula for calculating the area of a roof with a slope?

The formula for calculating the area of a roof with a slope accounts for the angle of the slope because a sloped roof's surface area is greater than the area of the horizontal projection of the roof. The appropriate formula to determine the actual area is linked to the cosine of the slope angle.

When you have a sloped roof, the angle of that slope affects how much additional area is present compared to a flat structure. The cosine of the slope angle essentially adjusts the horizontal dimensions (length and width) to reflect the actual slanted surface. By dividing the product of Length and Width by the cosine of the slope angle, you accurately calculate the real surface area.

This adjustment acknowledges that as the slope increases (toward vertical), the surface area becomes significantly larger than the basic rectangle defined by Length and Width alone. Hence, the correct formula correctly provides a method to compute the area of a roof accurately, accommodating its three-dimensional characteristics.