SOLUTION: Hi. I have a question about calculating surface area of a triangle with a triangular base. The base triangle has a base of 11 ft and a height of 9 ft. The actual height of the t

Algebra ->  Surface-area -> SOLUTION: Hi. I have a question about calculating surface area of a triangle with a triangular base. The base triangle has a base of 11 ft and a height of 9 ft. The actual height of the t      Log On


   

Question 1083040: Hi. I have a question about calculating surface area of a triangle with a triangular base. The base triangle has a base of 11 ft and a height of 9 ft. The actual height of the triangle is 13 ft. We need to compute the lateral area of the entire triangle.
First I computed the area of the base and came up with 49.5 ft (1/2 bh). For lateral area of lateral faces I came up with 212.91 ft. I used 1/2 pL formula to compute lateral area. Using Pythagorean theory computed lateral height at 14.1 ft. Then I computed perimeter of base to show that sides are 11 (given), 9.6 & 9.6 for a total of 30.2. Using these numbers I computed lateral area of triangular sides as (.5)(30.2)(14.1) = 212.91 ft. Adding the area of lateral sides to base my total surface area = 262.41 ft sq.
Can you check to make sure I did this right? THanks.
Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
"The base triangle has a base of 11 ft and a height of 9 ft. The actual height of the triangle is 13 ft."
QUESTION: Is the actual height of the triangle 9 or 13?
You calculated a side-slant height of 14.2, which means you used 9 for the height. So I'm confused about the 13.
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Finally, you say calculate the surface area of a triangle with a triangular base. IF it has a base it's a 3 dimensional object. So you must be talking about a triangular pyramid with four surfaces (three sides plus the base)?.
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The perimeter of the base is 11+14.1+14.1 = 39.2
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Please send me an email clarifying and I'll be delighted to help you.