What's the difference between interior and exterior angles of a triangle?

This question is answered by the picture below. You create an exterior angle by extending any side of the triangle.
Web page on the relationship between
exterior and interior angles of a triangle

Interior Angles of a Triangle Rule

This may be one the most card known mathematical rule-The sum of all 3 interior angles in a triangle is 180°.
As you can see from the picture below, if you add up all of the angles in a triangle the sum must equal 180°.
This property of a triangle's interior angles is simply a specific example of the
general rule for any polygon's interior angles.

To explore the truth of this rule, try
Math Warehouse's interactive triangle,
which allows you to drag around the different sides of a triangle and explore the relationship between the angles
and sides. No matter how you position the three sides of the triangle, the total degrees of all
interior angles (the three angles inside the triangle) is always 180°.

A triangle's interior angles are $$ \angle $$ HOP, $$ \angle $$ HPO and $$ \angle $$ PHO.
$$ \angle $$ HOP is 64° and m$$ \angle $$ HPO is 26°.
What is m$$ \angle $$ PHO?

the largest interior angle is opposite the largest side

the smallest interior angle is opposite the smallest side

the middle-sized interior angle is opposite the middle-sized side

To explore the truth of the statements you can use Math Warehouse's interactive triangle,
which allows you to drag around the different sides of a triangle and explore the relationships betwen the measures of angles
and sides. No matter how you position the three sides of the triangle, you will find that the statements in the paragraph
above hold true.

(All right, the isosceles and equilateral triangle are exceptions due to the fact that they don't have a single smallest
side or, in the case of the equilateral triangle, even a largest side. Nonetheless, the principle stated above still holds
true. !)