Congruent triangles-Need help (1 Viewer)

[Bulldog4lyf]

I have a really bad teacher for maths and she hasn't taught me anything about congruent triangles and I don't understand any of the questions relating to it. Please help, thank you.

 

[Kabuzo01]

Give me some questions you dont understand and I should be able to help, try going to the chapter in your text book and read the formula's or just post some questions and I'll explain it.

 

[Bulldog4lyf]

I can't find one at the moment, but I just don't know the whole thing, like side side side, side angle side, etc.

 

[Kabuzo01]

Do you have your text book with you? Or possibly a Year 9 text book?

 

[Bulldog4lyf]

I just read throught my text book and I got it. So is it side side side, angle angle angle, side angle side and right angle hypotenuse side???

 

[dc1337]

Triangles are congruent if they are:

SSS- All sides are equal
AAS- Two angles are equal and the given side is equal
SAS- Two sides are equal and the angle in between the sides are equal
RHS- In a Right Angled Triangle, the hypotenuse and another side is equal

 

[rolror88]

For congruency, there are 4 tests:

Source: New Century Text Book Year 10

 

[Brontecat]

There are a few basic rules:
SAS means side, angle, side - meaning that if the triangle has 2 of the same length sides (or scaled to the same) and a same size angle (again or scaled to the same) then it is congruent to in other words the same.
Other ones include
SSS - side, side, side
AAS - angle, angle, side

and there's one more i cant think of right now

 

[pwoh]

For congruency, there are 4 tests:

http://i436.photobucket.com/albums/qq86/theychoke/Congruency.jpg

Source: New Century Text Book Year 10

Hey we use the same textbook xD

 

[lyounamu]

4 tests as mentioned above:

SAS = 2 sides & angle between it
SSS = 3 sides
RHS = hypotenuse, another side in a RIGHT-ANGLED TRIANGLE
ASA = 2 angles and one side.

The reason why we can have all these varieties is that we can use all these properties to find prove that two triangles are exactly same.

So let's say we have two triangles having three same sides. Some people may question, "why are they congruent? They only have 3 sides equal! I don't understand the rule! (I don't really give a f*** about formula, tell me why!"

I will tell you why: if two triangles have three same sides, we can use this knowledge to find all the angles of each triangle (by using cosine angle rule which is cosA = (B^2+c^2-a^2)/2bc and you will see that if two triangles have same sides, all the angles are equal meaning that they are exactly congruent.

Same knowledge applies to other tests such as SAS, AAS and RHS.