Math 6A, Lesson 12, Spring 2017, 5/14/2017
1. Quiz on percentages
2. Points, Line and Planes
- Point: has position; has no size
- Line: has an infinite number of points; has no width; can be determined by two points; can be straight or curved
- Ray: a part of a line with one endpoint
- Endpoint
- Line segment: a part of a line between two end points; has length
- Plane: a flat surface; has no thickness
- Parallel lines: two lines on the same plane do not intersect (meet or cut)
- Perpendicular (lines) to each other: two lines intersect at right angle
- Foot of the perpendicular
3. Types of angles
- Acute angle: angle < 90 degree
- Right angle: angle = 90 degree
- Obtuse angle: 90 degree < angle < 180 degree
- Reflex angle: 180 degree < angle < 360 degree
4. Complementary, supplementary, and adjacent angles
- Complementary angles: the sum of two angles is 90 degree
- Supplementary angles: the sum of two angels is 180 degree
- Adjacent angles: two angles share a common side and a common vertex but do not overlap
5. Properties of Angles
- The sum of adjacent angles on a straight line is 180 degree
- The sum of all angles at a point is 360 degree
- Vertically opposite angles: when two lines intersect, the vertically opposite angles are equal
6. Home Work:
- Handout two pages
- Happy Mother’s Day! Do something special with your mother 🙂
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