[填空题]
An airplane travels at Mach 2.3 where the speed of so*kvpr 8 b8)uhkund is 310 m/oh7+j) zentvk bk3) u)s (a) What is tbjn)kz7) o 3hu v+e)kthe 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)
