The radius of the base and the height of a closed cylinder are 14 cm and 14 cm, respectively. The total surface area of the cylinder is equal to the area of a circle. What will be the diameter of the circle? [Use π = $\frac{22}{7}$]

56 cm

We know that,

The total surface area of the cylinder = 2πr(r + h )

The area of a circle =  πR² 

We have,

radius = 14 cm

height  = 14 cm

As per the question, 

The total surface area of the cylinder = The area of a circle 

2πr(r + h ) =  πR² 

2r(r + h ) = R² 

 2 × 14 (14 + 14 ) =  R²  

 R² = 28²   

R = 28 cm  

Diameter of the circle = 2 × 28 = 56 cm