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Răspuns:

Răspuns:

[tex]L=36=>Aria=L^2=36^2=1290m^2[/tex]

[tex]30g/m^2-rata[/tex]

[tex]10kg =[/tex]$[tex]15.80[/tex]

In total va folosi: [tex]30*1296=38880g=38.8kg[/tex](de fertiliser)

10kg......$15.80

38.8kg.......$x

=> x=[tex]\frac{38.8*15.8}{10}=61.304[/tex]$

Acum vom calcula cat va costa ptr. cele 3 semicercuri:

Deoarece latura patratului reprezinta diametrul care este egal cu 36m =>

raza = 18m

Aria unui semicerc este [tex]\frac{\pi r^2}{2}[/tex], iar a celor 3 semicercuri este [tex]3*\frac{\pi r^2}{2}[/tex]

Aria = [tex]3*\frac{\pi *18^2}{2}= \frac{3\pi *324}{2}=3\pi *162=1526.8m^2[/tex]

In total va folosi: [tex]30*1562.8=46884g=46.884kg[/tex]

10kg.....$15.80

46.884kg....$x

=>x=[tex]\frac{15.80*46.884}{10}= 74.07[/tex]$

Tot suma va fi = 74.07$+61.3$=134.37$

The surface of the lawn is:

[tex]\it S=3\cdot\dfrac{\pi R^2}{2}+\ell^2=3\cdot\dfrac{\pi\cdot18^2}{2}+36^2=3\cdot\dfrac{\pi\cdot18^2}{2}+18^2\cdot2^2=\\ \\ \\ =18^2\Big(\dfrac{3\pi}{2}+4\Big)\approx324\cdot\Big(\dfrac{3\cdot3.14}{2}+4\Big)=324\cdot8.71 \approx\ 2822\ m^2[/tex]

Required fertiliser is:

[tex]\it 2822\cdot30=84660g=84.66kg[/tex]

But, the fertiliser is only sold in 10kg bags, so :

[tex]\it 84,66 kg \approx 90kg \Rightarrow 9\ \ bags[/tex]

The cost is:

9 · 15.80 = 142.20 £