勾股定理16种证明方法( 四 )


∴ RtΔAED ≌ RtΔDMC.
∴ ∠EAD = ∠MDC,DC = AD = c.
∵ ∠ADE + ∠ADC+ ∠MDC =180o,M∠ADE + ∠MDC = ∠ADE + ∠EAD = 90o,
∴ ∠ADC = 90o.
∴ 作AB∥DC,CB∥DA,则ABCD是一个边长为c的正方形.
∵ ∠BAF + ∠FAD = ∠DAE + ∠FAD = 90o,
∴ ∠BAF=∠DAE.
连结FB,在ΔABF和ΔADE中,
∵ AB =AD = c,AE = AF = b,∠BAF=∠DAE,
∴ ΔABF ≌ ΔADE.
∴ ∠AFB = ∠AED = 90o,BF = DE = a.
∴ 点B、F、G、H在一条直线上.
在RtΔABF和RtΔBCG中,
∵ AB = BC = c,BF = CG = a,
∴ RtΔABF ≌ RtΔBCG .
∵c=S+S+S+S b=S+S+S a=S+S
S=S=S=S+S,
∴a+b=S+S+S+S+S
=S+S+S+(S+S)
=S+S+S+S
=c
∴ a+b=c.
【勾股定理16种证明方法】

勾股定理16种证明方法

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