Please solve this question

Don't know how to find x given these segment lengths

What is the best approximation for the area of a circle with a radius of 4 m ? use 3.14 to approximate pi

Every weekday, mr. jones bikes from his home to his job. sometimes he rides along two roads, the long route that is shown by the solid lines. other times, he takes the shortcut shown by the dashed line. how many fewer kilometers does mr. jones bike when he takes the shortcut instead of the long route?