The angle of elevation of an aeroplane from point A on the ground is 60°. After flight of 15 seconds, the angle of elevation changes to 30°. If the aeroplane is flying at a constant height of 1500√3 m, find the speed of the plane in km/hr.
Three successive discounts of 40%, 25% and 20%, respectively, on the marked price of a chair, are equal to a single discount of Rs.960. The marked price (in Rs) of the chair is:
If \(tan\space \theta-cot\space \theta = cosec\space \theta\), \(0^0<\theta<90^0\), then what is the value of \({2tan\space \theta-cos\space \theta\over \sqrt3cot\space \theta+sec\space \theta}\) ?