The curved surface area of a cylinder is half of its total surface area. If the height is 128 cm, then find the radius (in cm).

Correct option is A

Given:

Curved surface area (CSA) is half of total surface area (TSA)

Height h = 128 cm

Find radius (r)

Formula Used:

Cylinder: CSA = $$2\pi rh$$​​

TSA $$= 2\pi r(h + r)$$​​

Solution:

Given CSA $$= \dfrac{1}{2}\text{TSA}$$​​

​$$2\pi rh=\frac{1}{2}\times 2\pi r(h+r) \\ \ \\ 2h=h+r \\ \ \\ r=h=128\ \text{cm}$$​​