b)
[tex]P=8\pi cm^{2} \\\pi r^{2} =8\pi \\r^{2} =8\\r=\sqrt{8}=2\sqrt{2}cm[/tex]
[tex]l=2\pi r\\l=2\pi *2\sqrt{2}=4\sqrt{2}\pi cm[/tex]
d)
[tex]P=5\pi cm^{2} \\P=\pi r^{2} \\\pi r^{2} =5\pi \\r^{2} =5\\r=\sqrt{5}cm \\l=2\pi r\\l=2\pi *\sqrt{5} =2\sqrt{5}\pi cm[/tex]
e)
[tex]P=4\pi cm^{2} \\P=\pi r^{2} \\\pi r^{2} =4\pi\\r^{2} =4\\r=2cm\\l=2\pi r\\l=2\pi *2=4\pi cm[/tex]
h)
[tex]l=5\pi cm\\l=2\pi r\\2\pi r=5\pi \\2r=5\\r=\frac{5}{2} \\P=\pi r^{2} \\P=\pi * (\frac{5}{2}) ^{2}=\frac{25}{4} \pi =6\frac{1}{4} \pi cm^{2}[/tex]
