Bantu yg nomor 2 yang abcd makasih

ditanya Luas Lingkaran
rumus luas lingkaran =
L= π r²

 [tex]L =\frac{22}{7} r^{2} [/tex]

 r = 1/2diameter

maka

[tex]L= \frac{22}{7} (\frac{d}{2}) ^{2} \\ \\ L= \frac{22}{7} .\frac{d}{2} . \frac{d}{2}[/tex]

a. d=7cm
[tex]L= \frac{22}{7} (\frac{7}{2}) ^{2} \\ \\ L= \frac{22}{7} .\frac{7}{2} . \frac{7}{2}=38,5cm[/tex]


b. d=28
[tex]L= \frac{22}{7} (\frac{28}{2}) ^{2} \\ \\ L= \frac{22}{7} .\frac{28}{2} . \frac{28}{2}=616cm[/tex]

c. d = 1,4
[tex]L= \frac{22}{7} (\frac{1,4}{2}) ^{2} \\ \\ L= \frac{22}{7} .\frac{1,4}{2} . \frac{1,4}{2}=1,54cm[/tex]

d. d = 5,6
[tex]L= \frac{22}{7} (\frac{1,4}{2}) ^{2} \\ \\ L= \frac{22}{7} .\frac{5,6}{2} . \frac{5,6}{2}=24,64cm[/tex]

Mapel : Matematika
Materi : Bangun Datar - Lingkaran

[tex]a).\ d = 7\ cm\\ \\L=\frac{1}{4}\times \pi \times(d)^2\\ \\L=\frac{1}{4}\times \frac{22}{7}\times7\times7\\ \\L=5,5 \times7\\ \\L=38,5\ cm^2\\ \\ \\b).\ d=28\ cm\\ \\L=\frac{1}{4}\times \pi \times(d)^2\\ \\L= \frac{1}{4}\times \frac{22}{7} \times28\times28\\ \\L=22\times4\times7\\ \\L=616\ cm^2[/tex]

[tex]c).\ d=1,4\ cm\\ \\L=\frac{1}{4}\times \frac{22}{7} \times \frac{14}{10}\times \frac{14}{10}\\ \\L=11\times\frac{2}{10}\times\frac{7}{10}\\ \\L=11\times\frac{14}{100}\\ \\L=11\times0,14\\ \\L=1,54\ cm^2\\ \\ \\d).\ d=5,6\ cm\\ \\L=\frac{1}{4}\times \frac{22}{7} \times \frac{56}{10}\times \frac{56}{10}\\ \\L=22\times\frac{14}{10}\times\frac{8}{10}\\ \\L=22\times\frac{112}{100}\\ \\L=22\times1,12\\ \\L=24,64\ cm^2[/tex]

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