In right triangle $DEF$, we have $\angle D = 25^\circ$, $\angle E = 90^\circ$, and $EF = 9$. Find $DE$ to the nearest tenth. You may use a calculator for this problem.
F
9
E 25 D
tan D = EF / DE
tan 25° = 9 / DE
DE = 9 / tan 25° ≈ 19.3
