To find the measure of \( \angle COA \), we can use the fact that \( \angle BOA \) is a straight angle, meaning it measures 180°.
Given:
- \( m\angle BOA = 180° \)
- \( m\angle BOC = 110° \)
We know that the angles \( \angle BOC \) and \( \angle COA \) are adjacent angles that together make up \( \angle BOA \).
We can express this relationship with the following equation:
\[ m\angle BOA = m\angle BOC + m\angle COA \]
Substituting the known values into the equation:
\[ 180° = 110° + m\angle COA \]
To find \( m\angle COA \), we can rearrange the equation:
\[ m\angle COA = 180° - 110° \]
Calculating this gives:
\[ m\angle COA = 70° \]
Therefore, the measure of \( \angle COA \) is \( 70° \).
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