MAth 一問

Explanation as follows:

圖片參考：http://i238.photobucket.com/albums/ff245/chocolate328154/Maths528.jpg?t=1224673262

(a)>
assume

A(x1,0)
B(x2,0)
T(o,y1)

cause x^2+y^2-10x+8y+16=0

so when y=0,
x^2+0-10x+0+16=0
x^2-10x+16=0
(x-2)(x-8)=0
x=2,and x=8

when x=0,
y^2+8y+16=0
(y+4)^2=0
y=-4

so

the coordinates of point A(2,0) B(8,0) and T(0,-4)

2008-10-22 18:58:44 補充：
(b)>

the slope of AC is same with the BT

so the slope of AC = (-4-0)/(0-8) = 1/2

assume the coordinate of C is (x,y)

then the equation of AC is y-0=1/2(x-2)

>>>y=1/2x-1