plz solve no. 43 and PLZ send me the solution

    ​A solid cylinder of radius  ' r ' and height  ' h ' is vertically cut in to two equal parts, then the total surface area increased by _______

a             r h                 b           r 2 h               c             2   r h                 ( d )         4 r h

Dear student,
Here is the solution of your asked query:
Here r be the radius of cylinder and h be the height of the cylinder.TSA of Cylinder = 2πrh+2πr2          When Cylinder is cut vertically in to two equal parts we have;Each part will have two semi circular end , one curved  side and one rectangular side .Area of two semi circular ends=πr2Area of one curved side=πrhArea of one rectangular side=2rhTSA of one part=πr2+πrh+2rhTSA of the two parts=2 πr2+πrh+2rh So, Increase in total surface area=TSA of the two part-TSA of Cylinder                                                  =2 πr2+πrh+2rh-2πrh+2πr2                                                  =2πr2+2πrh+4rh-2πrh-2πr2 =4rhTherefore, increase in total surface area is 4rh.

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