Answer:
Explanation:
An example is as follows;
Using reference angle, evaluate
Solution:
We have:
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 positive
- 150 degrees is in the third quadrant where all cosine is negative
So, we have:
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