Calculate the volume of each solid. Where did the 15 come from?

Answer:
Using Pythagoras Theorem
Step-by-step explanation:
The triangle at the top is a right angled triangle with one side as 8cm and the hypotenuse is the length of the rectangle at the bottom which is 17cm.
By using pythagoras Theorem,
length of the other side
[tex]=\sqrt{17^2-8^2} \\=15[/tex]