Answer:
Length of base (a) = 5 units
Total Surface Area of Pyramid (T.S.A.) = ?
Now,
T.S.A. = Area of four triangles + Area of base
= [tex]4(\frac{\sqrt{3} }{4})(5^{2}) + 5^{2} = 25\sqrt{3} + 25[/tex] ≈ [tex]68.301sq. units[/tex]