#### Answer

a=9

#### Work Step by Step

The hypotenuse is 41 and the leg is 40. To find the other leg plug in b and c into the Pythagorean formula $a^{2}$ + $b^{2}$= $c^{2}$ --> $a^{2}$ + $40^{2}$= $41^{2}$:
$a^{2}$ + $40^{2}$= $41^{2}$ -simplify the exponent-
$a^{2}$ + 1600 =1681 - subtract 1600 from both sides-
$a^{2}$=81 -find the square root of 81 to solve for b-
a=9
A is 9.