Tonight’s Fun, and Next Meeting Info

Padhu led an excellent geometry session tonight. If you weren’t able to join us, here’s a question for you to ponder:

Consider a triangle with vertices at (0,2), (3,4) and (4,1).

  • What is the area of this triangle?
  • Show that the area of the triangle is equal to the following expression. (The expression is plus/minus one-half the determinant of the matrix formed by using the x-coordinates of the points in the first column, using the y-coordinates of the points in the second column, and using a value of 1 for each entry in the third column.)

Area Determinant

  • Why does the determinant formula work?

We spent a fair amount of time discussing the third question, and Padhu did an excellent job of connecting this topic from Algebra II to topics in the middle school math curriculum.

Next Meeting
Our next meeting will be Tuesday, December 13, 5:00-6:30pm, at the NCTM Headquarters in Reston, VA.

Will you be there? Please fill out this super-quick, one-question poll: NoVaMTC December Meeting.


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