KLynnTX Posted March 25, 2009 Share Posted March 25, 2009 I'm hoping someone will pull their book out, and help me out with a question. Lesson 61. Problem 13. Find the surface area of this triangular prism. The answer I'm getting is not what the answer book says. The area I'm getting for the sides is: 12 12 50.4 50.4 60.48 for a total of 185.28. The answer book has a different answer. Can anyone help me out? Quote Link to comment Share on other sites More sharing options...
KLynnTX Posted March 25, 2009 Author Share Posted March 25, 2009 . Quote Link to comment Share on other sites More sharing options...
Pam in MA Posted March 25, 2009 Share Posted March 25, 2009 Two triangular ends at 1/2(4x6) gives you 24. Two sides at 5x10 gives you 100. One side at 6x10 gives you 60, for a total of 24+100+60=184 sq. inches. Quote Link to comment Share on other sites More sharing options...
KLynnTX Posted March 25, 2009 Author Share Posted March 25, 2009 Except for the decimals that you didn't include,---(mine says that one side is 10.08 in)--- we are getting the same answer. But, the answer book claims the answer is 152.8 sq in. That can't be right, can it? Quote Link to comment Share on other sites More sharing options...
Bbunch5 Posted March 25, 2009 Share Posted March 25, 2009 What edition? I have the second edition solutions manual. [ 2(4x5) + 2(8)(6.3) + 4(8) ] sq in 2 [20 + 100.8 + 32 ] sq in 152.8 sq in Quote Link to comment Share on other sites More sharing options...
LinRTX Posted March 25, 2009 Share Posted March 25, 2009 If this is the secon edition: you have the two end triangles with a base of 4 and a height of 5 ,so area is .5bh=(.5)(4)(5)=10 sq. in. next are the two sides(rectangles) with sides 8 and 6.3, so area = (6.3)(8)=50.4 sq. in. last is the base (another rectangle) with sides of 8 and 4, so area is (8)(4)=32 sq. in. Adding all the sides: 10 + 10 + 50.4 + 50.4 + 32 = 152.4 sq. in. Does this help? Linda Quote Link to comment Share on other sites More sharing options...
Bbunch5 Posted March 26, 2009 Share Posted March 26, 2009 Adding all the sides: 10 + 10 + 50.4 + 50.4 + 32 = 152.4 sq. in. Re-do the addition and you should get 152.8 sq. in. Quote Link to comment Share on other sites More sharing options...
Puma Mom Posted March 26, 2009 Share Posted March 26, 2009 I have the 2nd edition and have it corrected in my answer book to be 152.8. My oldest must have caught this error. Of course, after that, he always thought the answer book was wrong and his answer was right!:D It sounds like the dimensions are different in different editions. In mine, the triangle part has sides 6, 5, and 5. The long side is 8.05. Area = [2(4*3)+2(5*8.05)+(6*8.05)] = 152.8 Quote Link to comment Share on other sites More sharing options...
LinRTX Posted March 26, 2009 Share Posted March 26, 2009 Thanks. I actually can add, but was typing fast because dinner was already late and I should not have been on the computer at all! Linda Quote Link to comment Share on other sites More sharing options...
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