Question

已知倾斜角为45º的直线L过点a（1.-2）和点b,点b在第一象限,且｜ab｜＝3√2.1

Answer 1

设:b(x,y) 3√2=√[(x-1)^2+(y+2)^2] , 18=(x-1)^2+(y+2)^2, 18=(x-1)^2+(x-1)^2, x-1=±3, x=-2或4 y=x-3 ,y=-5或1 ,点b坐标(-2,-5)或(4,1)x²/a²～y²＝1y=x-3 ,x²/a²-(x-3)²=1 , x²(1-a²)+6a²x-10a²=0 , x1+x2=-6a²/(1-a²) ,3a²/(1-a²)=4 ,a²=4/7 ,a=2√7/7