13. 在坐標平面上,設 k 為實數,若 ( 2,3)、( 4,–5)、( k ..-阿摩線上測驗
1F Sheng Yuan Wa 高二下 (2015/03/05)
三點共線,代表任兩點X,Y比相同 設A點(2,3),B點(4,-5),C點(k,-3) 算式是這樣:(X-X1)/(Y-Y1) = (X-X2)/(Y-Y2) 例如:B(4,-5)對A(2,3) = B(4,-5)對C(k,-3) (4-2)/(-5-3) = (4-k)/(-5-(-3)) => 2/-8 = 4-k/-2 => -4 = -32+8k => 28 = 8k => k= 3又1/2 (解法純參考用xD) |