30 degrees because you want to find the angle between the 150 degrees and it's supplement- if it was 340 then it would be 20 degrees
The reference angle for any angle in the coordinate system is defined as the acute angle (less than or equal to 90 degrees) made with the x-axis.
For an angle of 150 degrees, which is located in the second quadrant, the reference angle is found by subtracting the angle from 180 degrees, since 180 degrees is the line directly opposite the positive x-axis in the second quadrant.
Therefore, the reference angle for 150 degrees is: 180° - 150° = 30°.
This means that the reference angle, which is always positive and acute, for 150 degrees is 30 degrees.
The reference angle for 150 degrees is 30 degrees. This is determined by subtracting the angle from 180 degrees since it is located in the second quadrant. Therefore, 18 0 ∘ − 15 0 ∘ = 3 0 ∘ .
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