If a triangle has sides 8, 10, and z, which of the following cannot be the area of the triangle?


A. 3
B. 6
C. 12
D. 24
E. 46
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If the triangle is a right triangle with z being the hypotenuse, then the two legs 10 and 8 will be the base and height of the triangle. In that case, the area of the triangle is ½ x 10 x 8 = 40. This is the maximum area for a triangle with two sides of 8 and 10; thus, any area less than 40 is a possible value for the area. Thus, answer choice E cannot be the area of the triangle.

Answer: E
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Just use logic.
Think about it: given two sides and an unknown third - we can have a triangle with very very small area (almost 0), then the area increases and then finally starts decreasing again until it comes to 0 again. So there is a maximum limit to the area that the triangle can have. Hence given a range of increasing areas, the one which will not be possible is the largest one. For example, if 24 were not possible, 46 would not be possible too. But there is only one correct answer. Hence it must be 46 only.


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