一條數..唔識呀

A = πR^2 x (x/ 360)
L = 2πR x (x/360)

2 A/R = 2πR x (x/360) = L

So, R = 2A/L

2008-06-22 23:22:11 補充：
2 A/R
呢個只不過係..
當 A = πR^2 x (x/ 360) 時,,
張佢 乘 2
變左做
2 A = 2πR^2 x (x/ 360)
再張佢 除 R
2 A/R = 2πR x (x/360) = L

2 A/ R 就係咁黎GA喇!!!

L = 2πR (x/360)
Rearrange it, so...
R = L/[2π (x/360)]...... (1)

A = πR^2 (x/ 360)
Rearrange it, so....
R^2= A/[π(x/360)]
Sub (1) into a R of R^2

R x L/[2π(x/360)]= A/[π(x/360)]
兩邊各乘以[2π(x/360)]以消除份母....
RL = 2A
so,
R = 2A/L

1.
A=(1/2)RL
R=2A/L
2.
A=(R2x)/2
R=Sqrt(2A/x),where x is in radian

A + R + L - A - L = R