Final answer:
In mathematics, a reference angle is the acute angle formed by the terminal side of a given angle and the x-axis, used for angles in standard position. The reference angle for θ = 110° is 70° and for θ = 210° it is 30°.
Step-by-step explanation:
The concept of reference angles is often taught in mathematics, particularly in trigonometry to help understand the properties of angles in different quadrants of the Cartesian plane. A reference angle is always the acute angle (less than 90°) that the terminal side of the given angle makes with the x-axis. In standard position, the reference angle for an angle is the smallest angle between the terminal side of the angle and the horizontal axis (x-axis).
For an angle θ of 110°, which lies in the second quadrant, the reference angle would be 180° - 110° = 70°. Similarly, for an angle θ of 210° that lies in the third quadrant, the reference angle is calculated as 210° - 180° = 30°. Thus, the reference angle for θ = 110° is 70°, and for θ = 210°, it is 30°.