
Methods of proving triangles are congruent:
- Side-Side-Side (SSS) – we have to prove that all three sides are congruent.
- Side-Angle-Side (SAS) – what’s very important here is that the “Angle” is written between the two sides. ...
- Angle-Side-Angle (ASA) – just like the “angle” in SAS is in between two sides; the “Side” here should also be in between two angles.
- Angle-Angle-Side (AAS) – here, the “Side” is not in between two angles. You should not use an Angle-Side-Side (ASS) method or Side-Side-Angle (SSA) method. ...
- Hypotenuse-Leg (HL) – only used in right triangles.
- SSS (side, side, side) SSS stands for "side, side, side" and means that we have two triangles with all three sides equal. ...
- SAS (side, angle, side) ...
- ASA (angle, side, angle) ...
- AAS (angle, angle, side) ...
- HL (hypotenuse, leg)
How do you prove that two triangles are similar?
What are the similarity tests?
- Angle Angle Angle (AAA) If two angles of one triangle are respectively equal to two angles of another triangle, then the two triangles are similar. …
- Side Angle Side (SAS) …
- Side Side Side (SSS) …
- Right-angle Hypotenuse Side (RHS)
How can you say that triangles are congruent?
What is Triangle Congruence?
- Side – Angle – Side. Side Angle Side (SAS) is a rule used to prove whether a given set of triangles are congruent . ...
- Angle – Angle – Side. The Angle – Angle – Side rule (AAS) states that two triangles are congruent if their corresponding two angles and one non-included side are equal.
- Side – Side – Side. ...
- Angle – Side – Angle. ...
How to prove two triangles have the same centroid?
The important properties of the centroid of a triangle are:
- The centroid of a triangle is located at the intersecting point of all three medians of a triangle
- It is considered one of the three points of concurrency in a triangle, i.e., incenter, circumcenter, centroid
- The centroid is positioned inside a triangle
- At the point of intersection (centroid), each median in a triangle is divided in the ratio of 2: 1
How to find if right triangles are congruent?
With just that one diagonal, we know a tremendous amount about our polygon:
- We created two right triangles, △ GRI △ G R I and △ GN I △ G N I
- We know ∠GRI ≅ ∠GN I ∠ G R I ≅ ∠ G N I (right angles of a rectangle)
- We know ∠N GI ≅ ∠RI G ∠ N G I ≅ ∠ R I G (alternate interior angles of parallel lines intersected by a transversal, the diagonal)
- We know the hypotenuses of both triangles are congruent (GI G I; reflexive property)

How do you prove triangles are congruent?
Angle-Side-Angle (ASA) Rule Angle-side-angle is a rule used to prove whether a given set of triangles are congruent. The ASA rule states that: If two angles and the included side of one triangle are equal to two angles and included side of another triangle, then the triangles are congruent.
What are the 5 theorems that prove triangles congruent?
Thus the five theorems of congruent triangles are SSS, SAS, AAS, HL, and ASA.SSS – side, side, and side. ... SAS – side, angle, and side. ... ASA – angle, side, and angle. ... AAS – angle, angle, and side. ... HL – hypotenuse and leg.
What are the 3 ways to prove triangles similar?
You also can apply the three triangle similarity theorems, known as Angle - Angle (AA), Side - Angle - Side (SAS) or Side - Side - Side (SSS), to determine if two triangles are similar.
Is AAA a way to prove triangles congruent?
Knowing only angle-angle-angle (AAA) does not work because it can produce similar but not congruent triangles. When you're trying to determine if two triangles are congruent, there are 4 shortcuts that will work. Because there are 6 corresponding parts 3 angles and 3 sides, you don't need to know all of them.
What is SSS SAS ASA AAS?
Different rules of congruency are as follows. SSS (Side-Side-Side) SAS (Side-Angle-Side) ASA (Angle-Side-Angle) AAS (Angle-Angle-Side)
What are the 5 types of congruence?
Two triangles are congruent if they satisfy the 5 conditions of congruence. They are side-side-side (SSS), side-angle-side (SAS), angle-side-angle (ASA), angle-angle-side (AAS) and right angle-hypotenuse-side (RHS).
Does SSA prove Congruence?
Is SSA a Criterion for Congruence of Triangles? No, the SSA congruence rule is not a valid criterion that proves if two triangles are congruent to each other.
What is AAA similarity theorem?
Euclidean geometry may be reformulated as the AAA (angle-angle-angle) similarity theorem: two triangles have their corresponding angles equal if and only if their corresponding sides are proportional.
Is aas a similarity theorem?
For the configurations known as angle-angle-side (AAS), angle-side-angle (ASA) or side-angle-angle (SAA), it doesn't matter how big the sides are; the triangles will always be similar. These configurations reduce to the angle-angle AA theorem, which means all three angles are the same and the triangles are similar.
Is aas a congruence theorem?
In geometry, AAS means angle angle side and is one of the congruence theorems among the 5 different theorems that prove the congruency of two triangles.
Is HL a congruence theorem?
The hypotenuse leg theorem is a criterion used to prove whether a given set of right triangles are congruent. The hypotenuse leg (HL) theorem states that; a given set of triangles are congruent if the corresponding lengths of their hypotenuse and one leg are equal.
Side-Side-Side (SSS) Rule
Side-Angle-Side (SAS) Rule
- Side-Angle-Sideis a rule used to prove whether a given set of triangles are congruent. The SAS rule states that: If two sides and the included angle of one triangle are equal to two sides and included angleof another triangle, then the triangles are congruent. An included angleis an angle formed by two given sides. For the two triangles below, if AC = PQ, BC = PR and angle C< = angle P, then by …
Angle-Side-Angle (ASA) Rule
- Angle-side-angleis a rule used to prove whether a given set of triangles are congruent. The ASA rule states that: If two angles and the included side of one triangle are equal to two angles and included sideof another triangle, then the triangles are congruent.
Angle-Angle-Side (AAS) Rule
- Angle-side-angleis a rule used to prove whether a given set of triangles are congruent. The AAS rule states that: If two angles and a non-included side of one triangle are equal to two angles and a non-included sideof another triangle, then the triangles are congruent. In the diagrams below, if AC = QP, angle A = angle Q, and angle B = angle R, then triangle ABC is congruent to triangle QRP.
Three Ways to Prove Triangles Congruent
- A video lesson on SAS, ASA and SSS. 1. SSS Postulate:If there exists a correspondence between the vertices of two triangles such that three sides of one triangle are congruent to the corresponding sides of the other triangle, the two triangles are congruent. 2. SAS Postulate:If there exists a correspondence between the vertices of two triangles such that the two sides an…
Using Two Column Proofs to Prove Triangles Congruent
- Triangle Congruence by SSS How to Prove Triangles Congruent using the Side Side Side Postulate? If three sides of one triangle are congruent to three sides of another triangle, then the two triangles are congruent. 1. Show Video Lesson Triangle Congruence by SAS How to Prove Triangles Congruent using the SAS Postulate? If two sides and the included angle of one triangl…
SSS
SAS
- SASstands for "side, angle, side" and means that we have two triangles where we know two sides and the included angle are equal. For example: (See Solving SAS Trianglesto find out more)
Asa
- ASAstands for "angle, side, angle" and means that we have two triangles where we know two angles and the included side are equal. For example: (See Solving ASA Trianglesto find out more)
Aas
- AASstands for "angle, angle, side" and means that we have two triangles where we know two angles and the non-included side are equal. For example: (See Solving AAS Trianglesto find out more)
Hl
- This one applies only to right angled-triangles! HL stands for "Hypotenuse, Leg" (the longest side of a right-angled triangle is called the "hypotenuse", the other two sides are called "legs") It means we have two right-angled triangles with 1. the same length of hypotenuseand 2. thesame length for one of the other two legs. It doesn't matter which leg since the triangles could be rotated. Fo…
Caution! Don't Use "AAA"
- AAAmeans we are given all three angles of a triangle, but no sides. This is not enough information to decide if two triangles are congruent! Because the triangles can have the same angles but be different sizes: