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MathNet 2018-part-05 — 181 problems (EN–VI) Question 147

Math Olympiad Vault · MathNet 2018-part-05 — 181 problems (EN–VI)

Question 147

Let $\alpha$ and $\beta$ be the acute angles of a right triangle. Which of the following expressions is equivalent to the expression
$$
\frac{\sin \left(90^{\circ}-\alpha\right)+\cos \beta}{4 \sin \beta \cdot \cot \left(90^{\circ}-\alpha\right)}
$$
?

(A) $\frac{\sin \beta+\cos \beta}{4 \cos \beta}$

(B) $\frac{\sin \beta+\cos \beta}{4 \sin \beta}$

(C) $\frac{1}{4 \cos \beta}$

(D) $\frac{\sin \beta-\cos \beta}{4 \cos \beta}$

(E) $\frac{\sin \beta+\cos \beta}{2 \cos \beta}$