jika sebuah lingkaran memiliki luas 1.386.maka panjang jari jarinya adalah?? tolong sama cara nya yah....

[tex]L = \pi r {}^{2} \\ 1386 = \frac{22}{7} r {}^{2} \\ \frac{22}{7} r {}^{2} = 1386 \\ r {}^{2} = 1386 \div \frac{22}{7} \\ r {}^{2} = 1386 \times \frac{7}{22} \\ r {}^{2} = 4356 \\ r = \sqrt{4356} \\ r = 66[/tex]