Perpendicular Lines Two lines at right angles 90
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Perpendicular Lines Two lines at right angles (90 o) to each other Parallel Lines Straight lines that are always the same distance apart and never meet
Degrees: Measuring Angles We measure the size of an angle using degrees. Example: Here are some examples of angles and their degree measurements.
Protractor A device used to measure angles.
Types of Angles Right Angle Acute Angle Obtuse Angle
Right Angles • Angles with one corner equal to 90 degrees • It doesn’t matter which way the corner is facing
A“cute” Angles • Angles with one corner less than 90 degrees • It doesn’t matter which way the corner is facing
Obtuse Angles • Angles with one corner greater than 90 degrees • It also doesn’t matter which way the corner is facing
Lets Test Your Knowledge Here are some angles. Are they right, acute, or obtuse?
Complementary Angles Two angles are called complementary angles if the sum of their degree measurements equals 90 degrees. Example: These two angles are complementary.
These two angles can be "pasted" together to form a right angle! Making it complementary!
Supplementary Angles Two angles are called supplementary angles if the sum of their degree measurements equals 180 degrees. Example: These two angles are supplementary.
These two angles can be "pasted" together to form a straight line which is always 180 degrees!
Vertical Angles For any two lines that meet, such as in the diagram below, <AEB and <DEC are called vertical angles. <BEC and <AED are also vertical angles. Vertical angles have the same degree measurement.
ADD TO NOTES: Adjacent Angles Two angles are called adjacent angles if they share a common side and a common vertex Example: These adjacent angles. Who can name them?
Let’s use your prior knowledge to find the measures of the missing angles! F E 20 70 90 D C 70 J G 90 20 H
Let’s try another! B C 68 A 52 60 G 52 60 68 F E D