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If in right triangle $ABC$ right-angled at $B$ (shown in the figure), angle $A$ is acute, then which ratio equals $\tan A$? 
A$\dfrac{AB}{AC}$
B$\dfrac{BC}{AB}$
C$\dfrac{AC}{BC}$
D$\dfrac{AB}{BC}$
Answer & Solution
Correct answer: B. $\dfrac{BC}{AB}$
For angle $A$, the opposite side is $BC$ and the adjacent side is $AB$. Therefore $\tan A=\frac{\text{opposite}}{\text{adjacent}}=\frac{BC}{AB}$. The other options represent different trigonometric ratios.
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