82) What is the triangle area?

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ern5231: Master | Next Rank: 500 Posts; Posts: 226; Joined: Sun Aug 09, 2009 4:34 am

82) What is the triangle area?

by ern5231 » Wed May 12, 2010 10:07 pm

Three points (-2ï¼Œ4ï¼‰,(-6ï¼Œ-6),ï¼ˆ3ï¼Œ2ï¼‰form a triangle in the XY plane. What is the area of the triangle?

a) 7/91 b) 14/131 c) 15/65 d)19/22 e) 23/44

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Source: Beat The GMAT — Problem Solving | Wed May 12, 2010 10:07 pm

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Rahul@gurome: GMAT Instructor; Posts: 1179; Joined: Sun Apr 11, 2010 9:07 pm; Location: Milpitas, CA; Thanked: 447 times; Followed by:88 members

by Rahul@gurome » Wed May 12, 2010 10:42 pm

Area of the triangle when coordinates of the vertices are (x1, y1), (x2, y2), (x3, y3)
= {|x1 (y2 - y3) + x2 (y3 - y1) + x3 (y1 - y2)|}/ 2
= {|-2(-6 - 2) - 6 (2 - 4) + 3(4 + 6)|}/2
= {|16 + 12 + 30|}/ 2 = 58/2 = 29 square units, but none of the options has this as the answer.

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