Question

ABCD trapez isoscel, AB║CD, AD≡BC, AD=15cm, CD=5cm, ∡A=45°.

Aflati: a) linia mijlocie=? b) P=? A=? c) AC=?

Dau coroana!!!

Answer 1

Răspuns:

Explicație pas cu pas:Daca nu scrieti corect textul nu aveti nici o sansa sa le rezolvam

AB=15 si nu AD ( o litera si o virgula conteaza enorm in matematica )

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a)

Linia mijlocie= (B+b) /2

B=15

b=5

Lm= (15+5)/2

Lm= 20/2

Lm= 10 cm

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b)

ΔEDA ≡ ΔFCB (I.C )→ AE= FB = (15-5)/2=10/2= 5 cm

AE= 5cm

m∡A=45°→FD=AE=5cm

Pabcd = AB+AC+CD+AD

m∡EDA=45°→ΔEDA- isoscel →ED=EA=5cm→AD²=5²+5²→AD²=25+25→AD²=√50=5√2

P abcd = 15+5√2+5+5√2=20+10√2 cm

c)

A bcd= Lm* h

Lm=10

h=5

Aabcd= 10*5

Aabcd= 50 cm ²