#### Answer

c=.5

#### Work Step by Step

The Pythagorean Theorem states that for a right triangle, $a^{2} +b^{2} = c^{2}$. Thus, we plug in the values given for a, b, or c, and then we use these values to find the missing value:
$.3^{2} + .4^{2} = c^{2} \\\\ .25=c^{2} \\\\ c=.5$