JEE Main 2015 · 10 Apr · Shift 1 · Mathematics Q88

MathematicsSingle correct+4 / -1Question 88 of 90

In a ΔABC, $\dfrac ab=2+\sqrt3$ and ∠C = 60°. Then the ordered pair (∠A, ∠B) is equal to :

(15°, 105°)

(105°, 15°)

(45°, 75°)

(75°, 45°)

Answer and worked solution

Official answer: B

$A+B=120°$ and $\dfrac{\sin A}{\sin B}=2+\sqrt3$ . Check $(105°,15°)$ :
$\frac{\sin105^\circ}{\sin15^\circ}=\cot15^\circ=2+\sqrt3.\ ✓$

JEE Main 2015 · 10 Apr · Shift 1, Mathematics question 88