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1.总在Rt△ABC,∠C = Rt∠,AB=c,BC=a,AC=b (1).已知a:c = 1:2 ,求a:b (2)

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1.总在Rt△ABC,∠C = Rt∠,AB=c,BC=a,AC=b (1).已知a:c = 1:2 ,求a:b (2).已知a:b = 根号2:根号3
1.总在Rt△ABC,∠C = Rt∠,AB=c,BC=a,AC=b
(1).已知a:c = 1:2 ,求a:b
(2).已知a:b = 根号2:根号3,c =2根号5,求b
(1)设a=x,那么c=2x,根据勾股定理得b=根号下c^2-a^2=根号3倍的x,所以
a:b=1:根号3
(2)设a=根号2 *x,c=根号3 *x,那么根据勾股定理有(根号2 *x)^2+(根号3 *x)^2=c^2=20,解得x=2,所以b=2倍根号3