Answer
$A \approx 37^o$
Work Step by Step
RECALL:
In a right triangle,
$\sin{A} = \dfrac{\text{length of opposite side}}{\text{length of hypotenuse}}
\\\cos{A} = \dfrac{\text{length of adjacent side}}{\text{length of hypotenuse}}
\\\tan{A} = \dfrac{\text{length of opposite side}}{\text{length of adjacent side}}$
Use the sine formula to obtain:
$\sin{A} = \dfrac{\text{length of opposite side}}{\text{length of hypotenuse}}
\\\sin{A}=\dfrac{30}{50}
\\\sin{A} = 0.6$
Use the inverse function to obtain:
$A = \sin^{-1}{0.6}
\\A = 36.86989765^o
\\A \approx 37^o$
