## Angle Rules

**
**
- All the angles of a triangle add up to 180 degrees. So if you have
this triangle:

**
** **If a line MEETS another line, the two angles it makes with that line
add up to 180**^{o}.

These 2 angles are said to be *SUPPLEMENTARY*

Supplementary angles add up to 180^{o}.

**If a line CROSSES another line, then the angles across from each other
are the same.
**
Angle ? is 40^{o} because it is *across* from the
40^{o} angle.

Angle ? is 150^{o} because it is *across* from the
150^{o} angle
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**