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MAFS.912.G-CO.3.9

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Congruence, Similarity, Right Triangles & Trig - 46%

MAFS.912.G-


Circles, Geometric Measurement & Geometric Properties with Equations - 38%

MAFS.912.G-


Modeling with Geometry - 16%

MAFS.912.G-

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What You Need To Know...

MAFS.912.G-CO.3.9 - Prove theorems about lines and angles; use theorems about lines and angles to solve problems.

1. The benchmark will be assessed using Drag and Drop Response, Hot Text Response, Movable Text Response, Multi-select Response, Multiple Choice Response, Open Response, or Selectable Text.

2. Theorems are restricted to: vertical angles are congruent; when a transversal crosses parallel lines, alternate interior angles are congruent and corresponding angles are congruent; points on a perpendicular bisector of a line segment are exactly those equidistant from the segment's endpoints.

3. Items may have multiple sets of lines and angles.

4. Items may include narrative proofs, flow-chart proofs, two-column proofs, or informal proofs.

 

Example One

CO 3 9 ex1
 

Tonye is trying to prove that corresponding angles are congruent; specifically angles b and f are congruent. First he reasoned that angle b is congruent to angle d because of the Vertical Angle Theorem. Then he reasoned that angle d is congruent to angle h because they are corresponding angles. Lastly, angle h is congruent to angle f since they are vertical, therefore angle f is congruent to angle b by the Transitive Property of Congruence.

What is the flaw in Tonye’s reasoning? How could he correct his proof?

 

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Example Two

CO3 9 Ex2

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Example Three

CO3 9 Ex3

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Example Four

Example Five

Highlands Park is located between two parallel streets, Walker Street and James Avenue. The park faces Walker Street and is bordered by two brick walls that intersect James Avenue at Point C, as shown below.

 

1-3B

What is the measure, in degress, of ∠ACB, the angle formed by the park's two brick walls?

Answer grid

 
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Vertical Angles
Transversals
Points on a Bisector

Reference Sheet



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Select sample problems taken from FLDVIPN teacher materials

Violet Esopakis - Palm Beach Co.
Stephanie Fitzwater - Seminole Co.
Angela Kerins - Orange Co.
Lisa Lasseter - St. Johns Co.
Jeremy Lowery - Escambia Co.
Jodi Van Wagoner - Brevard Co.

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