An illustration shows a pyramid with a rectangular base of length 6 meters and width 2 meters. The perpendicular height from the apex to the center of the base is labeled 8.8 meters. The slant height from the apex to the center of the width of the rectangle is labeled 9 meters. Both heights are drawn as dotted lines. The sides that are not visible are shown in dashed lines.
When finding the surface area of the rectangular pyramid, what dimension will be used to find the height of the triangular sides?(1 point)