1. Warm-up 52° w x x 4x + 40x + 48 3x + 28 AC B

2. 4.2 Properties of Special Triangles Year 2 Geometry

3. Investigation #1(optional) Draw an angle on patty paper. Label the angle C. Put point A on one ray. Fold the patty paper so both rays match. Copy point A on the other ray and label it B. Construct line segment AB.

4. Investigation #1 continued What type of triangle is this? How can you tell? Name the vertex angle. Name the base. Name the base angles (2). ISOSCELES! TWO SIDES ARE CONGRUENT!

5. Isosceles Triangle Conjecture If a triangle is isosceles, then its base angles are ______________? CONGRUENT Base angles

6. Converse of the Isosceles Triangle Conjecture If a triangle has two congruent angles, then _________________________________? THE TRIANGLE IS ISOSCELES

7. Example #1 70° xx

8. Example #2 Find x and y. x y 24°

9. Example #3 Find x and the measure of each angle. 37° 106°

10. Wonderful Example #4 63° 58° e f g h k d c p a b n a=122°b=58°c=58°d=39°e=39°f=78°g=63° h=102°k=78°n=83°p=39° Find the missing angles

11. Summary Rewrite the Isosceles Triangle Conjecture and the Converse of the Isosceles Triangle Conjecture in your own words.

12. Homework Classwork  Worksheet Homework  Pg 206 1-8, 10,11, 21, 22