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J-Wang

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Can two quadrilaterals be said to be similar if, like triangles, their angles are equal?
 

RealiseNothing

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Can two quadrilaterals be said to be similar if, like triangles, their angles are equal?
Might just clarify that just because their angles are equal, doesn't make them similar. There are other conditions to fulfil as well.

However yes, it is possible for them to be similar given they meet the criteria of similar quadrilaterals.
 

jyu

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Can two quadrilaterals be said to be similar if, like triangles, their angles are equal?
No, e.g. a parallelogram and a rhombus with same 'corresponding' angles
 

J-Wang

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but if i have two quadrilatarals with angles in both quadrilaterals as; for example, 90, x, 90, 180-x in that order, then aren't they similar?

No, e.g. a parallelogram and a rhombus with same 'corresponding' angles
 

bleakarcher

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With a triangle the angles place restrictions on the sides which is why all that is required to two triangles to be similar is for their angles to be equal. In quadrilaterals, unlike triangles, there are so such restrictions on the lengths of the sides so more evidence is required to call two quadrilaterals similar.

Note: If two shapes are similar, they are the same in shape somehow.
 

jyu

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but if i have two quadrilatarals with angles in both quadrilaterals as; for example, 90, x, 90, 180-x in that order, then aren't they similar?
In your example you have provided extra specifications other than equal angles.
 
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Corresponding sides have to be in same ratio as well. Like for example you can have a 2x4 sided rectangle and another one that is 2x10.
Both have all angles of 90 degrees, but clearly they are not similar.
 

RealiseNothing

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but if i have two quadrilatarals with angles in both quadrilaterals as; for example, 90, x, 90, 180-x in that order, then aren't they similar?
Read above, corresponding opposite sides must have equal ratios.
 

barbernator

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i think it is safest to just say, that if the triangles within the quadrilateral are similar to the triangles in the other quadrilateral, and the angles are in the same cyclic order, then the quads are similar
 
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mirakon

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well if you draw a parallelogram with two angles x degrees and two angles y degrees, let this parallelogram be called Habib

Now if you imagine stretching one pair of parallel sides of Habib, then you will have a parallelogram with the same angles but one pair of sides of different length. Hence, the sides are of a different proportion to that of the original Habib and therefore the new parallelogram is not similar to Habib
 

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