[填空题]
An airplane travels at Mach 2.*hh+xkz,9 u)0mpzra h3 where the speed orw-9cf l u)s9kf sound is 310 m/s (a) What is t)srlkucf99 w-he angle the shock wave makes with the direction of the airplane’s motion? $^{\circ} $
(b) If the plane is flying at a height of 7100 m, how long after it is directly overhead will a person on the ground hear the shock wave? $\approx$ s (Round to the nearest integer)
