Math Arguments

Problems, Questions, and Puzzles to spark discussion and argument in the maths classroom.

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Strange Triangles

Triangle ABC is congruent to triangle DEF.

In triangle ABC, side AB measures 9, side BC measures 3x+18, and side CA measures 7.

In triangle DEF, side DE measures 9, side EF measures 2x+26, and side FD measures 7.

What equation would help you to solve for the side length of BC and EF?

What would you do to fix this question?

What other mathematical aspects of this caught your attention? What do you wonder about the situation?

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Notice, Wonder
Curmudgeon
GEOM

Source: Curmudgeon
(Actual question in an on-line geometry course.)

More Information:
Noticing and wondering is a tool to help students:
- Understand the story, the quantities, and the relationships in the problem.
- Understand what the problem is asking and what the answer will look like. Have some ideas to begin to solve the problem.
More Here at NCTM