ABCD trapez AB ll BC,
AB=25cm, BC=12cm, CD=10cm , AD=9cm
AD n BC=M
a) perimetrul ∆ MDC=24cm
b) aria ∆ MDC=p% din aria ∆ MAB
a)∆ MDC ≈∆ ABC {AB ll DC}
rapoartele de asemănare
MD/(AD+MD)=MC/(BC+MC)=DC/AB=10/25=2/5
5 MD=2AD+2MD
3MD=2AD=2×9 =>MD=18/3=6cm
5MC =2BC + 2MC
3MC=24. MC=24/3=8cm. CD=10cm
perimetrul MCD=6+8+10=24cm
b) raportul ariilor=(2/5)²
aria MCD/aria MBC=4/25
aria MBC ____100%
aria MCD_____p%
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ABCD trapez AB ll BC,
AB=25cm, BC=12cm, CD=10cm , AD=9cm
AD n BC=M
a) perimetrul ∆ MDC=24cm
b) aria ∆ MDC=p% din aria ∆ MAB
demonstrație
a)∆ MDC ≈∆ ABC {AB ll DC}
rapoartele de asemănare
MD/(AD+MD)=MC/(BC+MC)=DC/AB=10/25=2/5
5 MD=2AD+2MD
3MD=2AD=2×9 =>MD=18/3=6cm
5MC =2BC + 2MC
3MC=24. MC=24/3=8cm. CD=10cm
perimetrul MCD=6+8+10=24cm
b) raportul ariilor=(2/5)²
aria MCD/aria MBC=4/25
aria MBC ____100%
aria MCD_____p%
p= aria MCD ×100/aria MBC=400/25=16%