The length of ​ AB¯¯¯¯¯ ​ is 9 centimeters. A dilation with a scale factor of 2 is applied to ​ AB¯¯¯¯¯ ​ . What is the length of the image of ​ AB¯¯¯¯¯ ​ after the dilation is applied? Enter your answer in the box