d)
a
P=2(ab+ac+bc)
2(ab+ac+bc)=P
2ab+2ac+2bc=P
2ab+2ac=P-2bc
a(2b+2c)=P-2bc |:2b+2c
\frac{a(2b+2c)}{2b+2c}=\frac{P-2bc}{2b+2c}
a=\frac{P-2bc}{2b+2c}
e)
r
V= \frac{1}{3} \pi r^2 H
\frac{1}{3} \pi r^2 H=V |*3
\pi r^2H=3V |:\pi H
\frac{\pi r^2H}{\pi H}=\frac{3V}{\pi H}
r^2=\frac{3V}{\pi H}
r=\sqrt{\frac{3V}{\pi H}}
f)
według mnie o jedno r za dużo
R
V= \frac{4}{3} \pi R^3 |wzór na objętość kuli
\frac{4}{3} \pi R^3=V |*3
4\pi R^3=3V |:4\pi
R^3=\frac{3V}{4\pi}
R=\sqrt[3]{\frac{3V}{4\pi}}