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GBK Geometry. Jordan Johnson. Today’s plan. Greeting Review HW: General Triangle Area Theorem Lesson : Area Proofs Homework / Questions Clean-up. Review. Homework included: Tell how to find the area of a triangle. State that formula as a theorem, and add it to your conjectures log.
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GBK Geometry Jordan Johnson
Today’s plan • Greeting • Review HW: General Triangle Area Theorem • Lesson: Area Proofs • Homework / Questions • Clean-up
Review • Homework included: • Tell how to find the area of a triangle. • State that formula as a theorem, and add it to your conjectures log. • Set up the proof for it, and think about how you might prove it. • Log any other conjectures you come up with. • Bring in what you’ve written and drawn, for me to check off in class. • Find a partner. Discuss how you stated the theorem. • What is given? What is the goal?
Puzzle: Cube DissectionProgress? 3” x 3” wooden cube twenty-seven 1” x 1” cubes Possible with fewer than six cuts?
Homework • 25+ minutes: • Khan Academy recommendations • Practice with area proofs
Area Formulas • Area of a triangle = ½ bhwhere b is any side and h is the altitude to that side • Area of a parallelogram = bhwhere b is any side and h is the altitude to that side • Area of a trapezoid = ½(b1 + b2)hwhere b1 and b2 are the bases and h is the altitude
Clean-up / Reminders • Pick up all trash / items. • Push in chairs (at front and back tables). • See you tomorrow!