A=lb
a=100×40=4000cm^2
a=0.5×lb
a=0.5×40×30
a=600cm^2
a=4000+600
a=4600cm^2 hope it helps!!!!!!!!!!!!!!!!!!!!!!!!!!!
Step-by-step explanation:
The cylinder is a closed figure which consists of two circular ends. If r is the radius and h is the height of the cylinder, then its surface area is given by :

or

We also know that, surface area = perimeter×height
So, the surface area of the cylinder is the product of circumference of the circle and height of the cylinder.
Write the conjugates of them then FOIL both the top and bottom, then factor