Download Triangle Sum Theorem – Guided Practice

Triangle Sum Theorem – Guided Practice
1. What is the missing angle measure of a triangle when one
angle is 110 degrees and another is 25 degrees?
2. The angles of a triangle measure (5x + 8) degrees, (9x + 2)
degrees, and (15x – 4) degrees. What is the value of x? What
are the measures of the angles of the triangle?
The interior angle of a polygon is an angle that is on the
__________________ of the polygon and has its vertex formed
by two sides of the polygon.
Exterior angle of a polygon is an angle formed by a side of the
polygon and an _______________________ of an adjacent
side.
An exterior angle and its corresponding interior angle form a
straight line. Therefore, the two angles are
________________________.
Example: What is the measure of the missing angle below?
Example: An angle of a triangle has a measure of (3x + 1)
degrees. The corresponding exterior angle has a measure of (5x
– 13) degrees. What is the value of x? What are the measures
of the interior angle and the exterior angle?
Example: In Triangle PQR, the measure of angle Q is 45
degrees and the measure of angle R is 72 degrees. Find the
measure of angle RPQ.
Example: In triangle DEF below, find the value of x.
__________________________________________________
Exterior Angle Theorem: A measure of an exterior angle of a
triangle is equal to the sum of the measure of the two nonadjacent interior angles.
Example: Find the measure of an exterior angle at the base of
an isosceles triangle whose vertex angle measures 40 degrees.