Find the total area of the surface of a solid cylinder whose base radius is 4cm and height is 5cm
The correct answer is B. 72\(\pi\) cm2
The surface area of a solid cylinder can be calculated by summing the lateral surface area and the areas of the two circular bases.
1. Lateral Surface Area (LSA):
The lateral surface area of a cylinder can be calculated using the formula \(LSA = 2\pi r h\), where \(r\) is the base radius and \(h\) is the height.
Given \(r = 4\) cm and \(h = 5\) cm:
\[LSA = 2\pi \cdot 4 \cdot 5 = 40\pi \, \text{cm}^2\]
2. Area of Each Circular Base:
The area of a circle is given by the formula \(A = \pi r^2\).
Given \(r = 4\) cm:
\[A_{\text{base}} = \pi \cdot 4^2 = 16\pi \, \text{cm}^2\]
Since there are two circular bases:
\[2 \cdot A_{\text{base}} = 2 \cdot 16\pi = 32\pi \, \text{cm}^2\]
Now, add the lateral surface area and the areas of the circular bases to get the total surface area:
Total Surface Area = Lateral Surface Area + 2 × Area of Bases
Total Surface Area = \(40\pi + 32\pi = 72\pi \, \text{cm}^2\)
So, the total surface area of the solid cylinder is \(72\pi \, \text{cm}^2\).
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