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
$$ \sin \alpha = \frac{1}{2} $$
$$ \alpha = 30^{\circ} $$
$$ \therefore 3 \cos \alpha - 4 \cos^3 \alpha = 3 \cos 30^{\circ} - 4 \cos^3 30^{\circ} $$
Related Questions
- As observed from the top of a 100 m high light house
- If $ \triangle ABC \sim \triangle DEF $ and $ \angle A = 47^{\circ}, \angle E = 83^{\circ} $
- Evaluate: (3 sin 43°/cos 47°)^2
- An aeroplane is flying at a height of 300 m above the ground
- The shadow of a tower standing on a level ground is found to be 40 m
- From the top of a 7 m high building, the angle of elevation of the top