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# Pages 2 and 3 of 68

This is What We Have Learned 2
Topic 8 and 12
Let’s learn!
BY:JOSE CARLOS, SANTIAGO ORTIZ, LEANDRO MAURICIO AND JIMENA ZAPATA.
Topic 8
8 - 1 Basic Geometric Ideas
8 - 2 Measuring and Classifying Angles
8 - 3 Polygons
8 - 4 Triangles
8 - 6 Problem Solving: Make and Test Generalizations
8 - 1 Basic Geometric Ideas
Points and lines are basic geometric ideas. Lines are sometimes
described by relationships to other lines.
If you see a line crossing another line it means they intersect.
In this example you can se line U intersects line P.
If you see this time a dot it means it is point (a letter or number).
In this example point J.

Parallel lines can’t intersect because parallel means extending in the same direction, but without meeting.
8-2
Measuring and Classifying Angles
Right
In geometry and trigonometry, a right angle is an angle of exactly 90 degrees or \pi /2 radians corresponding to a quarter turn. If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles.
Acute
An acute angle is an angle that is less than 90°, and these angles can be measured using a protractor.
Obtuse
In Mathematics, “an obtuse angle is an angle which is greater than 90° and less than 180°”. In other words, an obtuse angle is between a right angle and a straight angle.
Straight
A straight angle is a 180° angle.
8-3 polygons
A polygon is a closed plane figure made up of line
segments. Common polygons have names that tell
the number of sides the polygon has.
Examples:
Octagon
Hexagon
8-4 triangles
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Examples:
equilateral triangle
Scalene triangle
Acute triangle
Right triangle