According to the meaning of the question, the angle DBA= 15 degrees. If the vertical line of point A intersects BD at point E, the angle BEA=75 degrees.

Therefore, the angle AED= 105 degrees, so the angle ADE=45 degrees.

Then draw a vertical line from point A to BD, where BD and F intersect. Because the angle AFD=90 degrees and the angle ADF=45 degrees, the length of AD can be calculated as 1500m, so the length of AF can be calculated.

Because the angle DBA= 15 degrees, the length of AF can be found, and the length of AB can be found with sin 15.