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Congruent means the same size and shape. Two triangles are congruent if the 3 sides and 3 angles of one are equal to the respective sides and angles, in order, of the other. Thus the triangles ABC and DEF are congruent if the lengths of AB and DE are equal, as well as BC and EF, and CA and FD, and the angle at A equals the angle at D, likewise that at B and at E, and of course if those two are true, the angle at C must equal the one at F since the 3 angles in a triangle always add up to 180 degrees. Two triangles are congruent if you can rigidly move one to exactly coincide with the other. It might be necessary to rotate it through 3-dimensional space, if the triangles are mirror images of each other.

There are some theorems that give criteria that guarantee triangles to be congruent. One is side-side-side, abbreviated SSS, meaning that if the sides of two triangles, in order, are equal, so are the angles. Another is SAS, meaning two sides of one triangle and the angle included between them are equal to the corresponding parts of the other. If 2 of the angles of two triangles are the same (AA), so is the third, and the triangles are similar (same shape, but not necessarily the same size). Then all you need is that one side and the corresponding side in the other triangle are equal to prove congruence. There is one ambiguous case: SSA. Depending on the length of the side opposite the given angle, there may be 0, 1, or 2 different (non-congruent) triangles having the given part measures: 0 if the side is too short, 1 if it is the length of the perpendicular to the other side, and 2 if it is longer than that.

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When they both have the same 3 interior angles and the same length of sides

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Q: When are two triangles said to be congruent?
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Related questions

If two triangles are congruent which of the triangles are congruent?

If they both have 3 sides the same and 3 angles the same then they are said to be congruent.


What do you call two triangles with proportional sides?

They are said to be similar but not congruent triangles.


What postulate or theorem verifies the congruence of triangles?

sssThere are five methods for proving the congruence of triangles. In SSS, you prove that all three sides of two triangles are congruent to each other. In SAS, if two sides of the triangles and the angle between them are congruent, then the triangles are congruent. In ASA, if two angles of the triangles and the side between them are congruent, then the triangles are congruent. In AAS, if two angles and one of the non-included sides of two triangles are congruent, then the triangles are congruent. In HL, which only applies to right triangles, if the hypotenuse and one leg of the two triangles are congruent, then the triangles are congruent.


What are three ways that you can prove that triangles are congruent?

If triangles have the corresponding sides congruent then they are congruent. SSS If two triangles have two sides and an included angle congruent then they are congruent. SAS If two triangles have two angles and an included side congruent then they are congruent. ASA SSA doesn't work.


In two triangles have a congruent angle and two congruent angle and two congruent sides then the triangles are guaranteed to be congruent?

Yes, if two triangles have two congruent angles and two congruent sides then the triangles are guaranteed to be congruent. They only need two angles and one side congruent or two sides and one angle in order to be congruent.


If two triangles have a congruent angle and two congruent sides then are the triangles guaranteed to be congruent?

Only if the congruent angle is the angle between the two congruent sides (SAS postulate).


The term for two triangles that are congruent after a dilation is?

The term for two triangles that are congruent after a dilation is similar.


Is it true that two triangles have 3 pairs of congruent angles then the triangle are not guaranteed to be congruent?

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Are two triangles are congruent if they have the same base?

No. All corresponding sides and angles have to be congruent for the triangles to be congruent.


If all corresponding sides and angles of two triangles are congruent those triangles are?

The triangles are also congruent.


What is c.p.c.t?

Corresponding Parts of Congruent Triangles is the full form od CPCT.


If any two sides and any angle are congruent in two triangles then the triangles must be congruent?

False