geometry

As follows:

Let an angle BAD be  β       β = 7º

1/       AD = cosβ * 3.7

2/      BD = sinβ * 3.7

3/      A_(ΔABD) = (AD * BD) / 2

4/      A_(ΔADC) = A(ΔABD) + 22.4

5/     CD = (2 * A_(ΔADC)) / AD

6/     b = sqrt( AD² + CD² )