In △ ABC, ∠ C = 90 °, De is the vertical bisector of AB on the line side, and the degree ratio of ∠ DAE to ∠ DAC is 2:1, so the degree of ∠ B can be calculated

In △ ABC, ∠ C = 90 °, De is the vertical bisector of AB on the line side, and the degree ratio of ∠ DAE to ∠ DAC is 2:1, so the degree of ∠ B can be calculated

The results show that: a + B = 90 °, DAE + DAC = a, and DAE: DAC = 2:1,
Then 3 ∠ DAC + B = 90 °
Because the distance from any point on the vertical bisector to both ends of the bisector line is equal, the angle is also equal, then ∠ B = ∠ DAE = 2 ∠ DAC,
Then 3 ∠ DAC + 2 ∠ DAC = 5 ∠ DAC = 90 °
It is concluded that ∠ DAC = 18 ° and ∠ B = 2 ∠ DAC = 36 degrees