[GBee]

Возможно надо представить b через искомую точку?
b1 = y0 - x0*tg(a1)
b2 = y0 - x0*tg(a2)

И тогда:


y1 - x1*tg(a1) = y0 - x0*tg(a1)
y2 - x2*tg(a2) = y0 - x0*tg(a2)

y1 - y0 = x1*tg(a1) - x0*tg(a1)
y1 - y0 = (x1 - x0)*tg(a1)
y0 = y1 - (x1 - x0) * tg(a1)

y2 - x2*tg(a2) = y1 - (x1 - x0) * tg(a1) - x0 * tg(a2)
y2 - x2*tg(a2) = y1 - x1 * tg(a1) - x0 * (tg(a1) - tg(a2))
x0 * (tg(a1) - tg(a2)) = y2 - x2*tg(a2) - y1 + x1 * tg(a1)

x0 = (y2 - y1 - x2*tg(a2) + x1*tg(a1))/(tg(a1) - tg(a2))
y0 = y1 - (x1 - x0) * tg(a1)

Вроде нигде не ошибся.