Warm Up

1. Warm Up Please draw the diagram. State the given and what you want to prove

2. Your Turn To Present! • With your Row, you will present 4.3 • 20 minutes to read over 4.3 • Come up with a plan on how you want to present the material • PowerPoint • Song/Dance • Poster Paper • Each group has 5 minutes to present the material • Everyone must present!

3. YOU WILL BE GRADED FOR THIS ASSIGNMENT • Count as class participation grade • I will be looking for: • Creativity (10 Points) • Content – Theorem and proof (20 Points) • Presentation (10 Points) • All members participating (10 Points) • MUST HAVE THE NEW THEOREM AND A PROOF FROM YOUR TEXTBOOK IN YOUR PRESENTATION! • BE CREATIVE…….GOOOOOOOOOOOOOOOO!

4. 4.3 A Right-Angle Theorem Apply one way of proving that two angles are right angles. T 23: If two angles are both supplementary and congruent, then they are right angles. 2 1 ~ Given: <1 = <2 Prove: <1 and <2 are right angles.

5. Proof: Since <1 and <2 form a straight angle, they are supplementary. Therefore, m<1 and m<2 = 180. Since <1 and <2 are congruent, we can use substitution to get the equation: m<1 + m< 2 = 180 or m<1 = 90 Thus, <1 is a right angle and so is <2.

6. You have graduated!!!!! You no longer need to write the words statement and reason at the top of each proof from now on!!!! Just make a T bar.

7. Given: Circle P S is the mdpt of QR Prove: PS QR Τ P S Q R

8. Given: ABCD is a rhombus AB = BC = CD = AD Prove: AC BD ~ ~ ~ Τ Hint: Draw and label shape! Use a Detour Proof