13. Calculate the height of a regular quadrilateral pyramid if: a) the length of the base edge is 10 dm and the side edges are 15 dm.
(b) the diagonal length of the base is 12 dm and the side edges are 14 dm;
(c) a base area of 16 m2 and a side edge length of 4 m;
(d) a base area of 60 m2 and a side edge length of 120 dm;
(e) the length of the base edge a meters and the side edge b meters; f) base area S m 2, and side edge length c meters.