You can
put this solution on YOUR website!You have a right triangle with an hypotenuse=17,000, a side=15,000 and an unknown height (the third side of the triangle).
17,000^2=15,000^2+x^2
289,000,000=225,000,000+x^2
x^2=289,000,000-225,000,000
x^2=64,000,000
x=sqrt64,000,000
x=8,000 ft was the altitude when the pilot began his glide.