橢圓

[HOLUKEN]

麻煩老師指導

[huanghs]

參考看看!

[thepiano]

作 PD 垂直 x 軸於 D
tan∠PAB = 1/2，tan∠PBA = -2，tan∠PBD = 2
可令 PD = 2k，BD = k，AB = 3k
由△PAB = (1/2) * AB * PD = 1，可求出 k = √3 / 3

2a = PA + PB = 2√5k + √5k
a = √15 / 2

2c = AB = 3k
c = √3 / 2

b = √3

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[HOLUKEN]

感謝兩位老師指導