A while walking towards a tower at a constant speed, observed that the angle of elevation of the top of the tower changed to 600 from 450. How much more than will he take to reach of the tower? (a) 5 min (c) 5 3 - 1 min (b) 5 3 min (d) None of these Share with your friends Share 2 Muskaan Talwar answered this Dear Student, Let AB be the tower, ∠C=45° and ∠D=60°Now, In ∆ABC,tan 45°=ABBC1=ABBCAB=BCIn ∆ABD,tan 60°=ABBD3=ABBDAB=3BDThus we get,BC=3BDBD+DC=3BDDC=3BD-BDDC=3-1BDSince the person walks at constant speed s, let t be time taken by him to cover CD.Thus, CD=stAlso let t' be time taken by him to cover BD.Thus, BD=st'Since, DC=3-1BD⇒st=3-1st'⇒t=3-1t'⇒t'=t3-1=t3+13-13+1=t3+12If t=5 minutes, then required time t'=53+12 min.Hence d is correct answer. Regards 0 View Full Answer