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Big Ideas:
Triangles can be described, classified, and analyzed by their attributes.
This lesson builds on the students' understanding of using the Pythagorean Theorem to find the missing lengths of sides of any right triangle. The task involves students in measuring the corners of an old house to determine how many walls and floors meet in right angles. They will now use the converse of the Pythagorean Theorem to determine if a triangle is a right triangle or not. If the sum of the squares of the shorter sides of the triangle are equal to the square of the longest side, then the triangle has a right angle. If the square of the longest side is less than or greater than the sum of the squares of the shorter sides, then the triangle does not have a right angle. The inequalities may also be used to identify which triangles have all acute angles and which triangles have an obtuse angle.
Vocabulary: converse, hypotenuse, legs , right triangle, acute angle, obtuse angle, right angle
Special Materials:
graph paper or isometric dot paper
ruler