# 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

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- Oppsite angle
- Two nonadjacent angles formed by two intersecting lines
- Vertical angle
- The right man on the right place at the right time
- Perpendicular lines cannot be skew lines
- Negative reciprocal
- 5-6 parallel and perpendicular lines
- Adjacent angles on parallel lines
- What does congruent mean
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- Relationship of angles
- Adjacent angle pairs
- Diagonal cross section of a triangular pyramid
- Adjacent supplementary angles examples
- Lesson 8 solve for unknown angles
- Module 15 angles and segments in circles answer key