Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$b=24$
In the given right triangle, $a$ and $b$ are the legs and $c$ is the hypotenuse. Using $a^2+b^2=c^2$ or the Pythagorean Theorem, with $a=7$ and $c=25 ,$ then \begin{array}{l}\require{cancel} a^2+b^2=c^2 \\\\ 7^2+b^2=25^2 \\\\ 49+b^2=625 \\\\ b^2=625-49 \\\\ b^2=576 \\\\ b=\sqrt{576} \\\\ b=24 .\end{array}