First, you have to find the central angle 360/3 ( 360 degrees divided by the amount of sides) = 120 then divide that by 2 = 60, so now you know that it's a 30 - 60 - 90 triangle. Then, you must use trigonometric ratios(SOH - CAH - TOA), in this case you need to use sin because you have the hypothenuse and your solving for x so you can use the opposite since you know your angle is 60. So then, Sin60 = x/9 ⇒ 9 * Sin60 = x. So, x = 7.7. Now, last but not certainly not least add the two segments together, 3.5 + 7.7 = 11.2
