tolong nomer 19-21 pakai caranya

Please, let me answer your question :)
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Mapel : Matematika
Tentang : Bangun Datar
Pembahasan :

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r : 56 cm
Keterangan : Bangun lingkaran hanya 3/4 bagian.

Ditanya : L?

L= 3/4 x 22/7 x 56 x 56
L= 3/4 x 22 x 8 x 56
L= 3 x 22 x 2 x 56
L= 66 x 2 x 56
L= 132 x 56
L= 7392 cm²

Yg C jawabannya.

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K = 176 cm

Ditanya = L?

K = πd
176 = 22/7 x d
d = 176/22/7
d = 176 x 7/22
d = 8 x 7
d = 56 cm
r = 28 cm

L = πr²
L = 22/7 x 28 x 28
L = 22 x 4 x 28
L = 88 x 28
L = 2464 cm²

Yg C jawabannya

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Persegi :
- s = 42 cm

Lingkaran :
- d = 42 cm > r = 21 cm

Ditanya = L arsir?

LP = s x s
LP = 42 x 42
LP = 1764 cm²

LL = 22/7 x r²
LL = 22/7 x 21 x 21
LL = 22 x 3 x 21
LL = 66 x 21
LL = 1386 cm²

L arsir = 1764 - 1386 = 378 cm²

Yg A jawabannya.

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Heil Manstein!

19.
3/4×22/7×56×56=7.392 cm^2
21.
luas arsiran = luas persegi - luas lingkaran
luas persegi = 42×42=1.764 cm^2
luas lingkaran = 22/7×21×21= 1.386 cm^2
luas arsiran = 1.764 - 1.386 = 378 cm^2