Answer:
1) 20°
2) 10°
3) 25°
4) 30°
Step-by-step explanation:
The reference angle is the acute angle formed by the terminal side of an angle and the x-axis.
Let θ be the terminal angle.
Let β be the reference angle.
If θ is in quadrant I: β = θ
If θ is in quadrant II: β = 180° - θ
If θ is in quadrant III: β = θ - 180°
If θ is in quadrant IV: β = 360° - θ
Angle 160° is in quadrant II. Therefore:
β = 180° - 160°
β = 20°
Angle 170° is in quadrant II. Therefore:
β = 180° - 170°
β = 10°
Angle 205° is in quadrant III. Therefore:
β = 205° - 180°
β = 25°
Angle 210° is in quadrant III. Therefore:
β = 210° - 180°
β = 30°
