[三角]

[LATEX]

請問一題測量的問題

[thepiano]

易知 PQBA 是等腰梯形，作 PE 垂直 AB 於 E
令 PA = x，PB = 15 - x，PQ = 2y，AE = 5 - y，BE = 5 + y
AB = 10，PE = (5/3)√10

(5 - y)^2 = x^2 - [(5/3)√10]^2
(5 + y)^2 = (15 - x)^2 - [(5/3)√10]^2
可求出 y = 5/2
PQ = 5