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jawabannya E
[tex]cos \: 30 = \frac{pq}{qr} \\ \frac{1}{2} \sqrt{3} = \frac{10}{x} \\ \frac{ \sqrt{3} }{2} = \frac{10}{x} \\ \sqrt{3} .x = 20 \\ x = \frac{20}{ \sqrt{3} } \times \frac{ \sqrt{3} }{ \sqrt{3} } \\ = \frac{20}{3} \sqrt{3} [/tex]