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## Geometry

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**Geometry**Chapter 11**InformalStudy of Shape**• Until about 600 B.C. geometry was pursued in response to practical, artistic and religious needs. Considerable knowledge of geometry was accumulated, but mathematics was not yet an organized and independent discipline. • Beginning in about 600 B.C. Pythagoras, Euclid, Thales, Zeno, Eudoxus and others began organizing the knowledge accumulated by experience and transformed geometry into a theoretical science. • NOTE that the formality came only AFTER the informality of experience in practical, artistic and religious settings! • In this class, we return to learning by trusting our intuition and experience. We will discover by exploring using picture representations and physical models.**Informal Study ofShape**• Shape is an undefined term. • New shapes are being discovered all the time. • FRACTALS**InformalStudyof Shape**Our goals are: • To recognize differences and similarities among shapes • To analyze the properties of a shape or class of shapes • To model, construct and draw shapes in a variety of ways.**NCTM Standard Geometry in Grades Pre-K-2**Children begin forming concepts of shape long before formal schooling. They recognize shape by its appearance through qualities such as “pointiness.” They may think that a shape is a rectangle because it “looks like a door.” Young children begin describing objects by talking about how they are the same or how they are different. Teachers will then help them to gradually incorporate conventional terminology. Children need many examples and nonexamples to develop and refine their understanding. The goal is to lay the foundation for more formal geometry in later grades.**Point**• Line • Collinear • Plane**If two lines intersect, their intersection is a point,**called the point of intersection. • Parallel Lines**Line segment**• Endpoint • Length**Half Line**• A point separates a line into 3 disjoint sets: The point, and 2 half lines.**The angle separates the plane into 3 disjoint sets: The**angle, the interior of the angle, and the exterior of the angle.**Degrees**• Protractor**Zero Angle: 0°**• Straight Angle: 180° • Right Angle: 90°**Acute Angle: between 0° and 90°**• Obtuse Angle: between 90° and 180°**Complementary angles**• Adjacent complementary angles**Supplementary Angles**• Adjacent Supplementary Angles**Lines cut by a Transversal – these lines are not**concurrent.**Transversal**• Corresponding Angles**Transversal**• Corresponding Angles**Parallel lines Cut by a Transversal**• Corresponding Angles**Parallel lines Cut by a Transversal**• Corresponding Angles**Describe the relative position of angles 3 and 5.**• What appears to be true about their measures?**Describe the relative positions of angles 1 and 7.**• What appears to be true about their measures?**The sum of the measure of the interior angles of any**triangle is 180°.**The measure of the exterior angle of a triangle is equal to**the sum of the measure of the two opposite interior angles.