Let's solve this geometry problem step by step.
1. Understanding the Problem:
* We are given \(\angle AOB = 123^{\circ}\), \(\angle AOD = 98^{\circ}\), and \(\angle AOC = 90^{\circ}\). We need to find \(\angle COD\).
2. Finding \(\angle BOD\):
* We know \(\angle AOB = \angle AOD + \angle DOB\). Therefore, \(\angle DOB = \angle AOB - \angle AOD\).
* Substituting the given values, we get \(\angle DOB = 123^{\circ} - 98^{\circ} = 25^{\circ}\).
3. Finding \(\angle COD\):
* We know \(\angle AOC = \angle AOD - \angle COD\). Therefore, \(\angle COD = \angle AOD - \angle AOC\).
* Substituting the given values, we get \(\angle COD = 98^{\circ} - 90^{\circ} = 8^{\circ}\).
4. Checking Result:
* \(\angle COB = \angle AOC + \angle AOB \implies \angle COB = 90 + 123 = 213^{\circ}\).
* \(\angle COD = \angle COB - \angle BOD = 213 - 25 = 188^{\circ}\).
* \(\angle AOD = \angle AOC + \angle COD = 90 + \angle COD = 98 \implies \angle COD = 98 - 90 = 8^{\circ}\).
Answer: 8 degrees