12^2+(11-9)^2=x^2---------------(Pyth.thm)
x=sqrt146,-sqrt146(rej.)
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perimeter:
sqrt146+11+9+12=44.08(cor. to 3 sig. figs)
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某長方形面積為(2x)cm^2,周界是(3x)cm,長和闊的差為(x/2)cm,求那長方形的周界。
You have given the answer,3x