The area of the base of a prism is 55 mm2. The perimeter of the base is 30 mm. The height of the prism is 7 mm.

What is the surface area of the prism?

A.
445 mm2

B.
320 mm2

C.
265 mm2

D.
92 mm2

Question

The area of the base of a prism is 55 mm2. The perimeter of the base is 30 mm. The height of the prism is 7 mm. 

What is the surface area of the prism?
 
 A.
445 mm2
 
 B.
320 mm2
 
 C.
265 mm2
 
 D.
92 mm2

anonymous · Answer

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This is a prism right?

anonymous · Answer

it does not show

anonymous · Answer

well I got an answer and I can show you my method.

anonymous · Answer

x+y = 30, xy =55
x(30-x)=55
$$30x-x ^{2}=55$$
$$x ^{?}-30x+55=0$$
$$\frac{ -b \pm \sqrt{b ^{2}-4ac} }{ 2a }\rightarrow \frac{ 30\pm \sqrt{(-30)^{2}-4(1)(55)} }{ 2(1) }$$

anonymous · Answer

so it B

anonymous · Answer

x=28.04 or 1.96

anonymous · Answer

oh kk thanx

anonymous · Answer

you got the answer? I was still trying to see which one

anonymous · Answer

I guess you already know because you have x and y from the quadratic formula since they are both positive values. use the smaller length for the base for the triangle

anonymous · Answer

umm yeah it is B 320 mm2

anonymous · Answer

hmm I didn't get that. Not sure how you did.

anonymous · Answer

surface area should be a sum of all the faces:
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