[surface area of the square pyramid]=area of the base+4*[area of one lateral triangle]
area of the base=12²----> 144 cm²
area of one lateral triangle=b*h/2
b=12 cm
h=slant height -----> 15 cm
area of one lateral triangle=12*15/2-----> 90 cm²
[surface area of the square pyramid]=144+4*[90]----> 504 cm²
the answer is
the surface area of the square pyramid is 504 cm²
