4.1 – Apply Triangle Sum Properties
A triangle is a polygon with three sides. A triangle
with vertices A, B, and C is called “triangle ABC”.
4.1 – Apply Triangle Sum Properties
Example 1:
Classify Triangle ABC by its sides and by its
angles.
4.1 – Apply Triangle Sum Properties
Example 2:
Draw an obtuse isosceles triangle and an
acute scalene triangle.
4.1 – Apply Triangle Sum Properties
When the sides of a polygon are extended,
other angles are formed. The original angles
are the interior angles. The angles that form
linear pairs with the interior angles are the
exterior angles.
4.1 – Apply Triangle Sum Properties
4.1 – Apply Triangle Sum Properties
Example 3: Find an angle measure.
Find m<JKM
4.1 – Apply Triangle Sum Properties
Example 4: Find an angle measure.
Find m<DEF
4.1 – Apply Triangle Sum Properties
A corollary to a theorem is a statement that
can be proved easily using the theorem.
4.1 – Apply Triangle Sum Properties
Example 5:
The support for a skateboard ramp shown
forms a right triangle. The measure of one
acute angle in the triangle is five times the
measure of the other. Find the measure of
each acute angle.