Move words to the blanks and equations to the boxes to prove that vertical angles 21 and 23 are congruent. Because linear pairs of angles are
and
Because angles that are
to the same angle are
it can be concluded that 21 23.
congruent
m21 +m22 = 180°
supplementary
m22 + m23 = 180°
m2l + m23 = 180°

Example 1: An ice cube being placed on the counter is an reversible effect on the ice cube because the ice cube is still an ice cube it doesn't change the elements of it.

Example 2: An egg being broken in a hot pan is a irreversible effect because you can't turn the egg back into its original form.

Hope this helps!