Zad. 7.
r=15m
P=\pi r^2=3*15^2\approx3*225=675[m^2]
Klasa ma 18 ucz.
675:18 \approx37,5[m^2] odp
Zad. 9
a)
Dane:
obw=16\pi cm
Obl. P
2\pi r=16\pi/:2\pi
r=8
P=\pi*8^2=64\pi[cm^2]
…
2\pi r=\pi/:\2\pi
r=0,5m
P=\pi*0,5^2=0,25\pi[m^2]
…
2\pi r= 0,12\pi mm/:2\pi
r=0,06 mm
P=\pi*0,06^2=0,0036\pi [mm^2]
…
2\pi r=\frac{2}{3} \pi km/:2\pi
r=\frac{2}{3}*\frac{1}{2}=\frac{1}{3}
P=\pi *(\frac{1}{3})^2=\frac{1}{9} \pi[km^2]
…
2\pi r=4dm/:2\pi
r=\frac{2}{\pi}
P=\pi *(\frac{2}{\pi})^2=\frac{4}{\pi}[dm^2]