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SMK Teknologi dan Rekayasa

Soal 56 Keliling Bangun Datar


Keliling\ bangun\ datar\ seperti\ pada\ gambar\ berikut\ ini\ adalah\ ....

a.\ \ 77\frac{1}{3}\ \ \ \ \ \ \ \ \ \ b.\ \ 87\frac{1}{3}\ \ \ \ \ \ \ \ \ \ c.\ \ 93\frac{2}{3}\ \ \ \ \ \ \ \ \ \ d.\ \ 97\frac{1}{3}\ \ \ \ \ \ \ \ \ \ e.\ \ 101\frac{2}{3}
Jawaban: b

Keliling\ bangun\ (yang\ diarsir)\\=panjang\ busur\ kecil\ +\ panjang\ busur\ besar\ +\ panjang\ dua\ garis\ datar
\frac{panjang\ busur}{keliling\ lingkaran}=\frac{sudut\ pusat}{sudut\ lingkaran}
\mathbf{Pada\ busur\ kecil}:
\frac{x}{2\pi r}=\frac{120^{\circ}}{360^{\circ}}=\frac{1}{3}
\begin{array}{rcl}x&=&\frac{1}{3}\times 2\pi r\\\\&=&\frac{2}{3}\times \frac{22}{7}\times 14\\\\&=&\frac{88}{3}\\\\&=&29\frac{1}{3}\end{array}
\mathbf{Pada\ busur\ besar}:\\(dengan\ cara\ yang\ sama\ seperti\ perhitungan\ pada\ busur\ kecil)
\begin{array}{rcl}y&=&\frac{1}{3}\times 2\pi R\\\\&=&\frac{2}{3}\times \frac{22}{7}\times 21\\\\&=&44\end{array}
\begin{array}{rcl}Keliling\ bangun&=&29\frac{1}{3}+44+2.7\\\\&=&73\frac{1}{3}+14\\\\&=&87\frac{1}{3}\end{array}

About Kalakay

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2 thoughts on “Soal 56 Keliling Bangun Datar

  1. Kakk 2.7nya drimana yakk… saya suka bingung klo menghadapi soal kayak gini kakk.. dibalas ya..:)

    Posted by Sheren prisscilya | 7 Maret 2014, 10:39 PM

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