Answer:
7π/18 radians
Step-by-step explanation:
A reference angle for angle β is the positive acute angle made by the terminal side of angle β and the x-axis.
A semi-circle angle has a measure of π radians.
The angle of the figure (in absolute value) can be decomposed as the addition of its reference angle and π radians. Therefore:
π + reference angle = 25π/18
reference angle = 25π/18 - π
reference angle = 7π/18 radians
