$\"\"$

Given pentagon

Prove: $\"\"$

Proof:

The sum of the measures of interior angles of a penatagon $\"\"$ .

The external angles $\"\"$ form 5 linear pairs with corresponding internal

angles.

Sum of the measures of external angles $\"\"$ sum of the measures of internal angles $\"\"$ $\"\"$ .

$\"\"$ (Subtract 540 from each side) $\"\"$

The sum of the measures of external angles of a pentagon is 360.