Answer:
the Pythagorean theorem must be applied 2 times
1) Calculate the diagonal of a right-angled triangle with sides of 3cm and 4cm.
d²= 3²+4²=25
d=√25=5
2) Calculate the diagonal sought in a right-angled triangle of dimensions 5 and 12
d²=5²+12²
d=√169 =13
length of the diagonal of the prism. 13cm