Pole powierzchni bocznej walca jest równa 60 II cm kwadratowym a pole powierzchni całkowitej 78 II cm kwadratowych . Oblicz pole podstawy
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Pb=60πcm²
Pc=78πcm²
Pc=2Pp+Pb
78πcm²=2Pp+60πcm²|-60πcm²
2Pp=18πcm²|:2
Pp=9πcm²
Pc = Pb + 2Pp
2Pp = Pc - Pb
2Pp = 78π - 60π
2Pp = 18π
Pp = 9π
Pp = πr²
πr² = 9π
r² = 9
r = 3
Pb = l * h = 2πr * h
2πr * h = 60π
2rh = 60
rh = 30
3 * h = 30
h = 10
V = Pp * h
V = 9π * 10
V = 90π
Proszę ;**