IDENTIDADES TRIGONOMÉTRICAS Demostrar las siguientes identidades 1. \( \cos \vee \tan v=\operatorname{sen} \downarrow \) 2. \( \cot \downarrow \cdot \tan v=1 \) 3. \( \operatorname{sen} \downarrow \cot v+\cos v \tan v=\operatorname{sen} v+\cos v \)

(d) Quando fazemos determinaçōes experimentais de uma grandeza \( X \), representamos seu valor numérico final acompanhado do erro \( \Delta X \) associado à medida, na forma \( X \pm \Delta X \). Para calcularmos o valor de uma funçāo \( f(X \pm \Delta X) \), utilizamos a regra \[ f(X \pm \Delta X)=f(X) \pm f^{\prime}(X) \Delta X \] Obtenha as fórmulas referentes a (i) \( \sin (X \pm \Delta X) \) e (ii) \( \cos (X \pm \Delta X) \)

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?

Solve \( \sin ^{2}(t)=-8 \cos (t) \) for all solutions \( 0 \leq t<2 \pi \)

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

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