Question

coroana....................​

Answer 1

Răspuns:

ABCD trapez

CE inaltime

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Aria=?

rezolvare\-----

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cos60=BE/BC

1/2=BE/12

BE=12/2=6

CD=AB-2BE=17-2*6=17-12=5cm

Determini inaltimea CE   din triunghiul dreptunghic BCE cu Pitagora

CE²=BC²-BE²

CE²=12²-6²=144-36=108

CE=√108=√36*3=6√3

Aria trapez ABCD=(AB+CD)*CE/2=(17+5)*6√3/2=

22*6√3/2=66√3cm²

Aria laterala =4*66√3=264√3

Aria bucatii de  stickla=50*50=2500cm²>264√3cm²

bunata de sticla este suficienta

Explicație pas cu pas: