To determine the measure of angle ROS, we need to subtract the given angles from 180 degrees, since the sum of the angles in a triangle is equal to 180 degrees.
First, let's find the measure of angle RPQ:
angle RPQ = 180 - (angle POQ + angle PQR)
angle RPQ = 180 - (21 + 58)
angle RPQ = 180 - 79
angle RPQ = 101 degrees
Next, let's find the measure of angle ROQ:
angle ROQ = 180 - (angle POQ + angle qos)
angle ROQ = 180 - (21 + 50)
angle ROQ = 180 - 71
angle ROQ = 109 degrees
Finally, to find angle ROS, we subtract the measures of angle RPQ and angle ROQ from 180 degrees:
angle ROS = 180 - (angle RPQ + angle ROQ)
angle ROS = 180 - (101 + 109)
angle ROS = 180 - 210
angle ROS = -30 degrees
It seems that the angle ROS has a negative measure, which is not possible in this context. Please double-check the given angles and make sure they are accurate.