H*cotα-h*cotβ=a or h/tanα-h/tanβ = a.

2. If Q is passed, QD is perpendicular to AP, and the extension line of AP passes through D; If you pass B, you pass BE parallel to AC and QC passes E.

Angle PBE= angle PAC = 15, angle QBE=60, so angle QBP=45.

Angle QAP= angle QAC- angle PAC = 45- 15 = 30.

In the right triangle QAD, the model of (1) is applied to QD, and QD = AB * Tanjiao QBP * Tanjiao QAP/ (Tanjiao QBP- Tanjiao QAP) = 10 * Tan45 * Tan30/(Tan45-Tan30) = 65438.

In right triangle PAC, because angle PAC = 15, angle APC = 75, angle QPD= angle APC = 75.

Pq = qd/sin75 = 5 * (root number 3+ 1)/sin75.