Question

A rectangle strip 5cm×25cm is rotated completely about the 25cm side. Find the total surface area so obtained​

Answer 1

Answer:

392.857

Step-by-step explanation:

total surface area of cylinder =

2*π* 5/2*25 = 392.857

Answer 2

The total surface area is 942.857 cm²

Step-by-step explanation:

• Given data

        Width of rectangle (B) = 5 cm

        Length of rectangle(L) = 25 cm

• If rectangle strip is rotated completely about the 25 cm side, it will form cylinder.

• Where

        Height of cylinder will be length of rectangle.

        Height of cylinder(H) = 25 cm

        Radius of cylinder will be width of rectangle.

        Radius of cylinder (R) = 5 cm

• We know the formula of total surface area of cylinder is given below

        T.S.A of cylinder = 2×π×R×(H+R)

        $\mathbf{T.S.A \ of\ cylinder=2\times \frac{22}{7}\times 5\times (25+5)}$

        On solving

        T.S.A of cylinder = 942.857 cm²