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Help can’t seem to figure out the base number?

Help can’t seem to figure out the base number?-example-1
User Tilo Mitra
by
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1 Answer

23 votes
23 votes

9514 1404 393

Answer:

B = 6.65 in²

Explanation:

The base area (B) is the area of the triangular base of the prism. You already know the sides of that triangle are 3, 5, and 7 inches. The figure shows the altitude to the side length 7 is 1.9 inches. The triangle area formula applies:

A = 1/2bh

A = 1/2(7 in)(1.9 in) = 6.65 in² . . . . area of one triangular base.

Then the area of one base is B = 6.65 in².

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The lateral area is the product of the perimeter and the height:

LA = Ph = 15(12) = 180 . . . . square inches

The total surface area is the sum of the lateral area and the areas of the two bases.

SA = LA + 2B

SA = 180 in² + 2(6.65 in²) = 193.3 in²

User Enessa
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