a door is in the shape of a rectangle surmounted by a semicircle whose diameter is equal to the width of the rectangle. if the perimeter of the door is 7 m, and the radius of the circle is r metres, express the height of the rectangle in terms of r

i found pretty easily h = 0.5 (7 - 4r - pi x r)

but the answer says 2r, not 4r. who is a making a mistake here? w = 2r right?