Appendix A - Review - A.2 Geometry Essentials - A.2 Assess Your Understanding - Page A19: 14

5

Since we have a right triangle with legs $a$, $b$ and the hypotenuse $c$, then by the Pythagorean theorem, we have $$c^2=a^2+b^2.$$ Thus, the hypotenuse is given by $$ c=\sqrt{a^2+b^2}=\sqrt{4^2+3^2}=\sqrt{25}=5 .$$