Answer:
[tex]\cos(150) = -\frac{\sqrt 3}{2}[/tex]
Explanation:
An example is as follows;
Using reference angle, evaluate [tex]\cos(150)[/tex]
Solution:
We have: [tex]\cos(150)[/tex]
150 degrees is in the second quadrant, and it makes 30 degrees (i.e. 180 - 150) with the x-axis.
This implies that, cos(150) has the same magnitude as cos(30);
The only difference in the values is the sign; because
30 degrees is in the first quadrant where all functions are positive150 degrees is in the third quadrant where all cosine is negativeSo, we have:
[tex]\cos(150) = -\cos(30)[/tex]
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[tex]\cos(30) = \frac{\sqrt 3}{2}[/tex]
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[tex]\cos(150) = -\frac{\sqrt 3}{2}[/tex]