Let ABCD be a rectangle, AB=a,BC=b. Consider the family of parallel and equidistant straight lines (the distance between two consecutive lines being d) that are at an the angle ϕ,0≤ϕ≤90∘, with respect to AB. Let L be the sum of the lengths of all the segments intersecting the rectangle. Find:(a) how L varies,(b) a necessary and sufficient condition for L to be a constant, and(c) the value of this constant. geometryrectanglegeometry unsolved