Hi Gaiz,

What’s up? (The sky)

Anyway, we are now going to do a bit of triangle congruence.

You’ll need to read a bit on Khai Yeep’s basics post first.

Triangle congruence basically shows you if the triangles are exactly the same. It is like triangle similarity just that riangle similarity proves that the triangles are proportionate – same shape – but we don’t know if they have the same size. So ppl, repeat after me.

Congruence – same shape, same size

Similarity – Same shape

In congruence (and similarity) we use the sides and angles of the triangles for comparison to prove their congruence (or similarity). Just remember

Angles control shape.

Sides control size.

In the criteria, S is used to refer to side. A is used to refer to angle.

Criteria for congruence:

1) SAS (not the special air service). It's the first pic below

2) AAS, it's the 2nd pic below

3) SSS, it's the third pic below

Before you all start cracking the obvious joke, ASS isn’t one of the criterion. (You can try to prove it, we’ll post the proof in the next post)

For right angled triangles,

4) SA

5) SS, it's the 4th pic below (RHS) – Right, Hypotenuse, Side

OK I’ll upload some techniques and explanations shortly.

We’ll also try to use a video / flash to illustrate the techniques.

Thanks