(on all odd numbered questions) can someone explain? starting on "copy and complete the statement"

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?

Is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis.

Given: △acm, m∠c=90°, cp ⊥ am , ac: cm=3: 4, mp-ap=1. find am.