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heather040200
Group Title
HELP! PIC BELOS I GIVE MEDALS:)
the lateral area of the right regular triangular prism is 18pi cm^2. find the total surface area. give your answer in decimal form rounded of to 2 decimal places
 one year ago
 one year ago
heather040200 Group Title
HELP! PIC BELOS I GIVE MEDALS:) the lateral area of the right regular triangular prism is 18pi cm^2. find the total surface area. give your answer in decimal form rounded of to 2 decimal places
 one year ago
 one year ago

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mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
The lateral area of the prism is the sum of the areas of the three rectangles whose dimensions are 3 and x.
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
Each rectangular face has an area of 3x, so all three faces have a combined area of 3 * 3x = 9x. The lateral area = 9x = 18pi
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
9x = 18pi x = 2pi
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
Now we need the area of the bases.
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
Each base is a regular triangle with side = 2pi
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
dw:1365464719385:dw
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
Each base of the prism is a regular (equilateral) triangle with side length of 2pi. If you drop an altitude, as the picture above shows, you create two 306090 triangles. The ratio of the lengths of the legs of a 306090 triangle is 1 : sqrt(3) Since the short leg measures pi, the long leg measures pi * sqrt(3) The long leg is the altitude of the large triangle, whose base measure 2pi
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
The area of a triangle is A = (1/2)bh Here we have A = (1/2)(2pi)(pi * sqrt(3) ) = pi^2*sqrt(3) Since there are two bases, the area of the 2 bases is 2*pi^2*sqrt(3)
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
Since the lateral area is 18pi, the total surface area is SA = (18pi + 2*pi^2*sqrt(3) ) cm^2 Now you can calculate an approximate value with your calculator.
 one year ago

heather040200 Group TitleBest ResponseYou've already chosen the best response.1
72.21
 one year ago

mathstudent55 Group TitleBest ResponseYou've already chosen the best response.1
I get 90.67
 one year ago
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