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Triangle or line

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Triangle or line Empty Triangle or line

發表  dalcde 周四 6月 10, 2010 4:11 pm

If the angles of a triangle are 180, 0 and 0 degrees, it becomes a "line" (refer to the figure at the bottom in the image). Do we still consider that as a triangle?
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發表  clovis_szeto 周四 6月 10, 2010 5:40 pm

I just think of if we are considering a triangle ABC, that is we have sides AB, AC and BC
we should remember one thing , that is the sum of 2 sides must larger than the other
that means
AB+AC>BC
but if we are talking about a line
it does not obey
so i would say a line is not a triangle!

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發表  dalcde 周四 6月 10, 2010 6:00 pm

So if AB+AC=BC, then it is not a triangle?
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發表  clovis_szeto 周四 6月 10, 2010 10:41 pm

i think so because of triangle inequalities

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發表  最靚仔既Henry 周日 6月 13, 2010 11:44 pm

how about 90-90-0 triangle?

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發表  dalcde 周一 6月 14, 2010 12:19 pm

For a ΔABC, where angle ABC = 90̊, angle BCA = 90̊ and angle CAB = 0̊, AB//AC(int. angles supp.), AB = AC(sides opp. equal angles), since parallel lines never meet unless they overlap, but AB and AC meet at A, therefore the two lines overlap each other, and B and C are at the same position, BC = 0. Since AB + BC = AB = AC, therefore ΔABC isn't actually a triangle, as it doesn't obey the triangle inequality. In fact if you try to draw it, it would be a line. Although cos(90̊), sin(90̊) etc. exist, and are equal to 0 and 1, it's just about a line, not a triangle. If you consider that line as a right-angled triangle and find the ratios, they do equal to 0 and 1.

By the way, you are absolutely not "靚仔". If you say that you are 最靚仔既Henry, then you are insulting every person named Henry by saying that they are all extremely ugly, as you say that they are uglier than you.
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發表  clovis_szeto 周一 6月 14, 2010 11:55 pm

哈哈, 我好有興趣知dalcde係邊個!!

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發表  dalcde 周二 6月 15, 2010 12:06 pm

Why?
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發表  clovis_szeto 周二 6月 15, 2010 6:34 pm

哈哈, 呢個世界可以寸HENRY 寸得咁應, 而MATHS 有番咁上下的SSC人只有數個...哈哈!

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