兩平行面距離 E ∶ + + + = 0 距 E ∶ + + + ′ = 0 平行,所以一樣 | − | ⟹ 距 = √ + + 17 + 2 + 3 = 5 2 − 5 | 7 | ex ∶ ⟹ = = 2 + 4 + 6 = 17 √ 1 + 2 + 3 √ 14 372