The aircraft A with radar detection equipment is flying horizontally at an altitude of 12 km and is increasing its speed at the rate of 1.2 m/s each second. Its radar locks onto an aircraft B flying in the same direction and in the same vertical plane at an altitude of 18 km. If A has a speed of 1000 km/h at the instant when θ = 30°, determine the values of ¨ r r¨ and ¨ θ θ¨ at this same instant if B has a constant speed of 1500 km/h.