The area of an expanding rectangle is increasing at the rate of 48 cm^2/sec. The length of the rectangle is always equal to the of the breadth. At what rate length is increasing at the instant when the breadth is 4.5cm?? Share with your friends Share 11 Rajat Sethi answered this Given,l=b2,⇒b=l..........(i)At b=4.5,l=4.52Now,Area of rectangle,A=l×b⇒A=l×l=l32Differentiating w.r.t time,dAdt=32l12.dldt⇒dldt=2dAdt3l∴dldtl=20.25=23×4820.25=649 57 View Full Answer Udit answered this Area of rect = l x b area = l^2 ( because - length is always equal to breadth ) differentiate w.r.t t dA/dt = 2l dl/dt 48 / 2l = dl/dt ( because - l=b=4.5 ) 48/ 9 = dl/dt 16/3 cm/s = dl/dt -16 Radhika G answered this Thanks! but the is a word I missed, length is always equal to square of breath 10
