题目

Finally, the long-awaited flying car is almost here. AeroMobil, a Slovakian company, plans to start selling its creation, the AeroMobil3. 0, in 2017. The company claims on its site that the vehicle “transforms in seconds from an automobile to an airplaneby using “existing infrastructure created for automobiles and planes.The vehicle is petrol-powered and has wings that fold, which allows it to be parked like a car, though it is nearly 20 feet long. The company's website features a video where the AeroMobil 3. 0 drives out of a hangar (飞 机棚 ）and goes down a highway, shari一个圆锥的母线长为5，高为4，则这个圆锥的侧面积是________．