Placing Figures on Coordinate Plane

1. Use the origin for vertex or center of figure.

2. Place at least one side on an axis.

3. Keep the figure within the first quadrant if possible.

4. Use coordinates that make computations as simple as possible.

"Nothing is ever achieved without enthusiasm." Ralph Waldo Emerson

Put these steps into your notes for today’s class

Mrs. Motlow Classroom Procedures

Obtaining Help: C3B4ME

1. If you need help, ask a classmate.

2. If not helped, ask another classmate.

3. If still not helped, ask the 3rd and final

classmate.

4. If still in need of help, raise your hand.

5. I will come to your desk to provide assistance or ask you to come to my desk.

If it is a common question, let me know so we can share the

answer with the class.

6. After being helped, quietly return to your

seat.

You are responsible

for helping other

classmates when

asked!

Page 297 8 – 30 Even8. Translation or reflection

10. Rotation

12. reflection, rotation or translation

14. Reflection

16. Translation

18. ABC is translation

20. XYZ is a rotation

22. Translation and rotation

24. Rotation

26. Translation

28. Vertical, A, H, I, M, O, T, U, V, W, X, Y

Horizontal B, C, D, E, H, I, K, O, X

Chapter 4.8 Triangles and Coordinate Proof

Objective: Write coordinate proofs and be able to position and label triangle for coordinate proofs.

CLE 3108.3.1 Use analytic geometry tools to explore geometric problems involving parallel and perpendicular lines, circles, and special points of polygons.

CLE 3108.4.3 Develop an understanding of the tools of logic and proof, including aspects of formal logic as well as construction of proofs.

Spi.3.2,Use coordinate geometry to prove characteristics of polygonal figures.

Placing Figures on Coordinate Plane

1. Use the origin for vertex or center of figure.

2. Place at least one side on an axis.

3. Keep the figure within the first quadrant if possible.

4. Use coordinates that make computations as simple as possible.

"Nothing is ever achieved without enthusiasm." Ralph Waldo Emerson

Practice

1. Position and label and isosceles triangle JKL on a coordinate plane so that the base JK is a units long.

2. Use the origin as vertex J

3. Place the base of the triangle along the positive x axis

4. Position the triangle in the first quadrant.

5. Place vertex K at position (a, 0) to make JK a units long

6. Since JKL is isosceles, position point L ½ way between point J and K or at x coordinate a/2. Height is unknown, label b.

J K(0, 0)

(0, a)

L (a/2, b)

Find the missing coordinates

F

(?, ?)

E(0, a)

G (?, ?)

• Name the missing coordinates of the Isosceles right triangle EFG.

• Given E (0, a)• F (?, ?)

• (0,0)• G (?, ?)

• (a, 0), because isosceles triangle

Find the missing coordinates

Q

(?, ?)

S(?, ?)

R (c, 0)

• Name the missing coordinates of the Isosceles right triangle QRS.

• Given R (c, 0)• Q (?, ?)

• (0,0)• S (?, ?)

• (c, c), because isosceles triangle

Coordinate Proof• Write a coordinate proof to prove that the measure of the

segment that joins the vertex of the right angle in a right triangle to the midpoint of the hypotenuse is one half the measure of the hypotenuse.

A

(0, 0)

B(0, 2b)

C

(2c, 0)

P(?, ?)

• Given: Right ABC, P midpoint BC• Prove: AP = ½ BC

Midpoint

Page 303 Example 4

Scalene Triangle

Practice Assignment

• Page. 304 10 – 28 even