3. A cottage located in the Swiss Alps has an attic that is in the face shape of an isosceles triangle, where the width (base) is 18 ft. and the

height is 10 ft. The depth of the cottage is 40 ft. long. (See sketch below which is only showing the attic part of the cottage.) The attic is filled with insulation that has the following density function (units/ft'), 8(h) = 45 – 2h, where h is the distance from the floor of the attic.