200 likes | 209 Views
Learn about the Angle Sum Theorem, Third Angle Theorem, Exterior Angle Theorem, and Remote Interior Angles in triangles. Practice finding missing angle measures and applying the theorems.
E N D
Lesson 4-2 Angles of Triangles
Ohio Content Standards: Establish the validity of conjectures about geometric objects, their properties and relationships by counter-example, inductive and deductive reasoning, and critiquing arguments made by others.
Ohio Content Standards: Make and test conjectures about characteristics and properties (e.g., sides, angles, symmetry) of two-dimensional figures and three-dimensional objects.
Theorem 4.1Angle Sum Theorem The sum of the measures of the angles of a triangle is 180.
Find the missing angle measures. 43° 79° 2 1 74° 3
Theorem 4.2Third Angle Theorem If two angles of one triangle are congruent to two angles of a second triangle, then the third angles of the triangles are congruent.
Exterior Angle Angle formed by one side of a triangle and the extension of another side.
Exterior Angle Angle formed by one side of a triangle and the extension of another side. 1
Remote Interior Angles Interior angles of the triangle not adjacent to a given exterior angle.
Remote Interior Angles Interior angles of the triangle not adjacent to a given exterior angle. 2 3
Theorem 4.3Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles.
Find the measure of each numbered angle in the figure. 38° 32° 4 5 3 1 2 41° 64° 29°
B C 20° A