Question

Ajutor la problema 7

Answer 1

[tex]\mathcal{P}=AB+BC+CD+AD=\frac{28}{5}\\ din\:desen\:AD=BC=\frac{x}{5}\\ \\ deci\\ \mathcal{P}=AB+CD+2AD=\frac{28}{5} \\ 2\cdot\frac{x}{5}+x-1+x+1,5=\frac{28}{5}\\ \\ \frac{2x}{5}+2x-1+\frac{15}{10}=\frac{28}{5}\\ \\ aducem\:la\:acelasi\:numitor,\:10\\ \\ \frac{4x+20x-10+15}{10}=\frac{56}{10}\\ \\ 24x+5=56\\ 24x=51\\ \\ x=\frac{51}{24}=\frac{17}{8}[/tex]
[tex]AB=x-1=\frac{17}{8}-1=\frac{9}{8}\\ AD=BC=\frac{17}{8}\codt\frac{1}{5}=\frac{17}{40}\\ DC=\frac{17}{8}+\frac{15}{10}=\frac{170+120}{80}\frac{290}{80}=\frac{29}{8}[/tex]

Answer 2

Insumam laturile:
(x-1)+x/5+(x+1,5)+x/5= 28/5 cm
x-1+x/5+x+1,5+x/5=28/5
2x+2x/5 = 28/5+1-1,5
(10x+2x)/5 =28/5-0,5 
12x/5=(56-5)/10
12x/5=51/10 => 120x=255
x=255/120=51/24= 2,125cm
AB=2,04-1 =1.125cm
BC=AD =2,125/5 = 0,425cm
CD= 2.125+1,5 =3,625 cm