If $ \sin\alpha = \frac{1}{2} $, then find the value of $ 3 \cos \alpha − 4 cos^3 \alpha $
Trigonometry (10)If $ \sin\alpha = \frac{1}{2} $, then find the value of $ 3 \cos \alpha − 4 cos^3 \alpha $
Answer
$$ \sin \alpha = \frac{1}{2} $$
$$ \alpha = 30^{\circ} $$
$$ \therefore 3 \cos \alpha - 4 \cos^3 \alpha = 3 \cos 30^{\circ} - 4 \cos^3 30^{\circ} $$