WARM UP Draw and label one of each of the following triangles: (Be sure to include all necessary notations) 1.Obtuse 2.Scalene 3.Right 4.Isosceles 5.Acute 6.Equilateral

ACTIVITY: TRIANGLE SUM THEOREM 1.Get out a scratch piece of paper. 2.Using a ruler draw a large-ish triangle on your paper. 3.Cut out your triangle. 4.Tear two corners off the triangle. 5.Position the two torn-off corners next to the third angle as shown in the picture. Tape the two corners in place. 6.Make a conjecture about the sum of the measures of the angles of a triangle and write it on the back of your triangle. 7.Put the triangle with your name on it in your box on the back/side counter

SECTION 3.5 THE TRIANGLE SUM THEOREM

NOTES The Triangle Sum Theorem The sum of the measures of the angles of a triangle is 180  The Parallel Postulate Given a line and a point not on the line, there is one and only one line that contains the given point and is parallel to the given line.

NOTES Draw the picture below and then copy and complete the following table in your notes: m1m1m2m2m  1 + m  2m3m3m4m4 30  70  30  80  110  70  110  40  80  120  60  120  40  90  130  50  130 

NOTES An angle such as  4 that forms a linear pair with an angle of a polygon is called an exterior angle. The angles of the polygon at the other vertices are called remote interior angles of the exterior angle. In the diagram  1 and  2 are remote interior angles of  4. Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the remote interior angles.

WORKSHEET Complete the 3.5 Worksheet and then turn into your box on the back/side counter. Pick up a Project sheet once you are finished, read through the project and begin brainstorming and sketching your project design. Check out homework on side board.