\( 3 + \operatorname { an } 30 ^ { \circ } - \operatorname { cosec } 60 ^ { \circ } + 5 \cot 45 ^ { \circ } \)

(1) จงหาค่าของ \( 2 \sin 20^{\circ}+\cot 68^{\circ} \)

When evaluating the expression \( \tan ^{-1}\left(-\frac{\sqrt{3}}{3}\right) \), the angle obtained is ...

Given that \( \tan 75^{\circ}=2+\sqrt{3} \) hence determine \( \tan 15^{\circ} \) leaving your answer in the form \( a+b \sqrt{c} \)

Solve \( 8 \sin \left(\frac{\pi}{5} x\right)=4 \) for the four smallest positive solutions

6 A plane flies on a true bearing of \( 280^{\circ} \mathrm{T} \) at \( 600 \mathrm{~km} / \mathrm{h} \) after taking off at 1300 hours. To the nearest kilometre, how far north of its starting position is it at 1530 hours?