ANGLES - Geometry Jargon

Naming Sides

Corresponding Parts

Congruent Shapes

Congruent Clues

Similar Shapes

Equilateral Triangles

Isosceles Triangles

ANGLES: are named using 1 or 3 letters

EXAMPLE 1:   $\angle R\ =\ 82\degree$  

EXAMPLE 2:   $\angle QRS\ =\ 82\degree$  

SIDES: are named using  2 letters

EXAMPLE 1:   $\overline{QR}$  =  $\overline{RQ}$  

EXAMPLE 2:   $\overline{RS}$  =  $\overline{SR}$  

"Matching" angles or sides

WITHIN SAME IMAGE:  Use locations to find matching parts ("Both are top-left")

SHAPES:  Always line up the names to find matching parts (ignore the picture)

EX:   $\Delta ABC$  vs

        $\Delta GHI$  

 $\angle A$  corresponds to  $\angle G$  

 $\angle B$  corresponds to  $\angle H$  

 $\overline{AC}$  corresponds to  $\overline{GI}$  

All Corresponding Angles are equal

All Corresponding Sides are equal

Essentially...same shape, same size

The shape may be turned or flipped.

Equal sides are shown with "tic marks"

EXAMPLE:

Equal angles are shown with "arches"

EXAMPLE: 
 $\angle C=\angle F$  since both have 2 arches

The congruent symbol:   $\cong$  

 $\Delta ABC\cong\Delta DEF$   means all their matching parts are equal (twin shapes)

All Corresponding Angles are equal

All Corresponding Sides are proportional (times the same amount)

Essentially...same shape, different size.

THINK: Giant or Miniature version

CAN BE: bigger or smaller

CANNOT BE: fatter or thinner

Similar symbol:  $\approx$  

 $ABCD\approx WXYZ$  means one is a "giant" version of the other

The sides grew (times the same factor)

The angles did not change