Context: Right triangle with 30° angle at bottom-right, right angle at bottom-left, base = 66. Find $x$ (vertical side).

Answer: B: $22\sqrt{3}$

Why: 30-60-90 triangle with side ratios $1 : \sqrt{3} : 2$. Base 66 is opposite 60°, $x$ is opposite 30°. $\dfrac{x}{66} = \dfrac{1}{\sqrt{3}}$, so $x = \dfrac{66}{\sqrt{3}} = \dfrac{66\sqrt{3}}{3} = 22\sqrt{3}$.

Traps: A ($22$) divides by $3$ instead of $\sqrt{3}$. C ($66\sqrt{3}$) multiplies instead of divides. D ($132$) doubles the base.