Question

Find the surface area of the solid below. Circle the letter of the

correct answer.
A 32.5 in.
B 210 in.
C 225 in.
D 240 in.

Alex choose D as the correct answer. What did she do wrong?

Answer 1

D

Explanation:

Answer 2

The correct answer is C.

Explanation:

Begin by finding the SA of the rectangular prism. The formula is:

2lh + 2lw + 2hw

L = length

w = width

h = height

Plug in the numbers based on what they give you. Your equation should look like this: (2x6x6) + (2x6x2.5) + (2x6x2.5)

The length of the rectangular prism is 6in. The width is 2.5 in. The height is 6in.

Solve your equation. (2x36) + (2x15) + (2x15)

-----------------------------> (72) + (30) + (30)

---------------------------------> (102) + (30) = 132 sq. in.

Now find the SA of the triangular prism. ATTN: DO NOT FIND THE AREA OF THE RECTANGLE THAT IS NOT ON THE OUTSIDE OF THE PRISM. THIS IS WHAT ALEX DID WRONG.

For the SA of the triangular prism, find the area of each side, except that of which is not on the outside of the figure and find the sum.

Your equation should look like this:

(1/2bh) + (1/2bh) + (area of rectangle 1) + (area of rectangle 2)

(1/2x6x8) + (1/2x6x8) + (10x2.5) + (8x2.5)

(1/2x48) + (1/2x48) + (25) + (20)

(24) + (24) + (25) + (20)

(48) + (45) = 93 sq. in.

Now, add the areas of both figures.

132 + 93 = 225

So, the correct answer is C. , 225 square inches.

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