Step-by-step explanation:
By the property of intersecting chords inside a circle we have:
[tex]x \times 2x = 8 \times 9 \\ \\ \therefore \: 2 {x}^{2} = 72 \\ \\ \therefore \: {x}^{2} = \frac{72}{2} \\ \\ \therefore \: {x}^{2} = 36 \\ \\ \therefore \: {x} = \sqrt{36} \\ \\ \therefore \: {x} = 6 \\ \\ \therefore \: 2 {x} = 2 \times 6 = 12 \\ \\ [/tex]
