$\cos \left( - 240 ^ { \circ } \right)$

Name: $\cos \left( - 240 ^ { \circ } \right)$
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Question

Quizplus · Accepted Answer

The cosine function is even, meaning $\cos(-\theta) = \cos(\theta)$. Therefore, $\cos(-240^\circ) = \cos(240^\circ)$. The angle of 240° corresponds to the third quadrant where cosine is negative. The reference angle for 240° is 60°, and $\cos(60^\circ) = \frac{1}{2}$, thus $\cos(240^\circ) = -\frac{1}{2}$.

cos⁡(−240∘)\cos \left( - 240 ^ { \circ } \right)cos(−240∘) A) −12- \frac { 1 } { 2 }−21​

$\cos \left( - 240 ^ { \circ } \right)$ A) $- \frac { 1 } { 2 }$