迷惑中
幼苗
共回答了30个问题采纳率:90% 举报
(1)函数y=x, 设p点座标为(m,m)
则AP斜率为m-2/m, 由于PQ⊥AP, 则PQ斜率为-m/(m-2)
PQ的方程为 y-m=-m/(m-2)(x-m)
取x=0, 得y=2m-2, 即Q(0,2m-2)
AP=V[(m-2)^2+m^2]
PQ=V[(0-m)^2+(2m-2-m)^2=V[(m-2)^2+m^2]
所以AP=PQ
(2) 上述m=a, b=2m-2=2a-2
(3)S△AOQ=1/2 OP*OQ = 1/2 *2 * (2m-2)=2m-2
S△APQ=1/2AP*PQ = 1/2 [(m-2)^2+m^2]
S△AOQ=2/3 S△APQ
2m-2 = 1/3 [(m-2)^2+m^2]
6m-6 = 2m^2 -4m +4
m^2-5m +5 =0
m=(5+-V5)/2
P=(m,m)
1年前
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