



 
Hi Megan, Here is my diagram of your problem. R is the position of the radar station, P is the position of the plane when it is directly above the station and S is the position of the plane t minutes later. You know that RP = 3 km, the measure of the angle SPR is 180^{o} + 30^{o} = 210^{o} and the plane is flying at 330 km/hr which is 330/60 km/minute. Thus PS = (330/60) × t km. Use the law of cosines to write an expression for RS as a function of t. Differentiate this expression to arrive at an expression for the rate at which RS is increasing and evaluate when t = 1 minute. Harley  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 