a-maths!!!!!!

x = (1-t²)/(1+t²)
y = 2t/(1+t²)

x^2 + y^2
= (1-t²)^2 / (1+t²)^2 + 4 t^2 / (1+t²)^2
= [ (1-t²)^2 + 4 t^2 ] / (1+t²)^2
= [ 1 - 2 t² + t^4 + 4 t^2 ] / (1+t²)^2
= [ 1 + 2 t² + t^4 ] / (1+t²)^2
= (1+t²)^2 / (1+t²)^2
= 1
x^2 + y^2 = 1

2007-09-14 19:03:30 補充：
慢左, 不過好似我個簡單 D, 你話係咪?請多多支持 <~~~~~~~~~ 拉票大行動

方法唔同姐, 都唔算簡單咗好多......( 你都識講好似啦 )
你個「拉票大行動」實在非常令人討厭!!!

As follows~~~


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