Chapter 6 - 6.7 - Applications and Models - 6.7 Exercises - Page 494: 9

$A=36.87°$ $B=53.13°$ $C=90°$ $a=3$ $b=4$ $c=5$

$c^2=a^2+b^2$ $c^2=3^2+4^2=9+16=25$ $c=\sqrt {25}=5$ $sin~A=\frac{opp}{hyp}=\frac{a}{c}=\frac{3}{5}=0.6$ $A=arcsin~0.6=36.87°$ $sin~B=\frac{opp}{hyp}=\frac{b}{c}=\frac{4}{5}=0.8$ $B=arcsin~0.8=53.13°$ $C=90°$ because it is a right triangle.