Perimeter and Area of Triangles in the Cartesian Plane

Pupils figure out how to be resourceful when tasked with finding the area of a triangle knowing nothing but its endpoints. Beginning by exploring and decomposing a triangle, learners find the perimeter and area of a triangle. They then work with the coordinates of the vertices of the triangle to create a formula for the area of the triangle. 

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CCSS: Designed
Instructional Ideas

  • Use graphing white boards as scholars explore the patterns in the triangles
Classroom Considerations

  • Provide graph paper to individuals for them to use as they explore the examples in the lesson
  • Uses the distance formula to determine lengths of sides of triangles on the coordinate plane
  • The ninth lesson in a series of 15
Pros

  • Provides teacher notes and questioning suggestions throughout the lesson
  • Includes answer keys for the lesson, practice problem set, and opening and closing activities
Cons

  • Quickly moves to abstract formulas; learners can find the indicated measures without using the formulas
Common Core