Triangle Maths

 The date is wrong - Not sure when this was originally written 

 

Chris is doing triangles in maths at school and every so often I have to dig deep into the memory banks to help.
Today's question:
Triangle PQR ~ Triangle DEF
Determine the length of DF
If PQ = 10cm, DE=5cm, PR=6cm

Hmm.  What does a ~ mean in the land of triangles.
Well this web site  tells me

Similar (same shape, different size)

DEFMNO

Triangle DEF is similar to triangle MNO

and Similar means

Similar

Two shapes are Similar if the only difference is size (and possibly the need to turn or flip one around).

Resizing is the Key

If one shape can become another using Resizing (also called dilation, contraction, compression, enlargement or even expansion), then the shapes are Similar.


OK so I hope this means that the two triangles have the same shape and therefore all the same angles.