The answer is 16. Explaination- In the right triangle (Altitude)^2+(base)^2=(hypotenuse)^2 (15)^2+(base)^2=(17)^2 225+(base)^2=289 (Base)^2=289-225 (Base)^2=64 Therefore Base=8 units Since it is a square pyramid, (base of right triangle)=1/2(one side of pyramid’s base) 8*2=(lenght of one side base)