原帖由 ericchim 於 2010-4-8 05:27 PM 發表
for any point on the circle~
For example, now S=(a,b)
slope of OS = (b-0)/(a-0) =b/a
slope of SP = (b-0)/(a-p) =b/(a-p)
as OS perpendicular to SP (converse of angle in semi- circle)
angle O ...
原帖由 ericchim 於 2010-4-8 10:49 PM 發表
alternative answers are enclosed with rectangles
i am not very understood why the 2nd answer is x^2+y^2-px+pa-a^2-b^2=0...
but it just the same as the first one as pa-a^2-b^2 =0
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