I don’t know if this is right or not, can you tell me where I went wrong?

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The Velociraptors

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So, I have two ways to solve this, but I’m getting different answers.
I’ll only mention the one that is easier to explain however, unless I’m asked to do otherwise.
The first way I thought it would be was area of hemisphere+area of side+area of base.
So, 32pi+120pi+16pi= approx. 527.79.
But again, I’m not confident about this, and I’m looking for a way to get the correct answer.
 
A hemisphere does NOT have any sides. You are asked to find the surface area of just the hemisphere, not of the cylinder. OK?
 
The Velociraptors said:
So it would be 2*pi*4^2 which would be approximately 100.53 cm^2?
Click to expand...
IMO why give an approximate surface area. The answer is 32pi cm^2.

BTW the question asked for the EXACT surface area, so no your answer is not correct.

In your original answer the 120cm should be 240cm. The circumference of circle is 2pi*r!
 
Jomo said:
IMO why give an approximate surface area. The answer is 32pi cm^2.

BTW the question asked for the EXACT surface area, so no your answer is not correct.

In your original answer the 120cm should be 240cm. The circumference of circle is 2pi*r!
Click to expand...
Because (1/2)(4pi)(4^2)?
so, the 30 is completely irrelevant.
 
The Velociraptors said:
Because (1/2)(4pi)(4^2)?
so, the 30 is completely irrelevant.
Click to expand...
Where did the (1/2)*4 come from? The surface area for the sides of a cylinder is 2pi*r*h. Now (1/2)*4 =2 so what you wrote is not wrong but unusual.

If you were to unfold the sides of a cylinder you get a rectangle. In your case the height is 30cm and the base is 2*pi*4cm. Is this clear?
 
Jomo said:
Where did the (1/2)*4 come from? The surface area for the sides of a cylinder is 2pi*r*h. Now (1/2)*4 =2 so what you wrote is not wrong but unusual.

If you were to unfold the sides of a cylinder you get a rectangle. In your case the height is 30cm and the base is 2*pi*4cm. Is this clear?
Click to expand...
Yes it’s clear. Thank you.
 
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