In a rhombus, opposite angles are equal and adjacent angles are supplementary. Since angle A (m∠A) is given as 114°, we can determine angle B as follows:
- Since angles A and B are adjacent angles in the rhombus, their sum should be 180°: \[ m∠A + m∠B = 180° \]
- Plugging in the value of angle A: \[ 114° + m∠B = 180° \]
- To find angle B, we subtract 114° from 180°: \[ m∠B = 180° - 114° = 66° \]
Therefore, the measure of angle B (m∠B) of rhombus ABCD is 66°.