VOCAB
What do you call a part of a line that has one endpoint and goes on forever in one direction?
HINT: This is the "arm" of an angle
Ray
An angle measures 75 degrees. Which scale on the protractor would you use if the angle opens to the right?
OUTER scale, starting at 0.
An angle that measures less than 90 degrees is called what?
Acute angle
Two angles together form a right angle. One measures 30 degrees. What is the other?
60 degrees. These complementary angles add up to 90
What symbol do we use to show perpendicular lines?
An upside-down T symbol
What tool do we use to measure angles?
Protractor
What is the measure of a quarter turn?
90 degrees.
An angle that measures more than 90 degrees but less than 180 degrees is called what?
An obtuse angle
Two angles are on a straight line. One measures 110 degrees. What is the other?
70 degrees. Angles on a straight line add up to 180.
What does perpendicular mean?
Two lines that meet at a right angle (90 degrees)
What are the two scales on a protractor called?
The inner and outer scale
What is the measure of a half turn?
180 degrees.
An angle that measures exactly 90 degrees is called what?
A right angle
An unknown angle and a 45-degree angle together make a right angle. Find the unknown.
45 degrees
What does parallel mean?
Two lines that never meet. They stay the same distance apart forever.
What unit do we use to measure angles?
Degrees
What is the measure of a full turn?
360 degrees
True or false: a straight angle is also called a half turn.
True — both equal 180 degrees
Three angles are on a straight line: 60, 80, and an unknown. Find the unknown.
40 degrees.
60+80+40=180
True or false: perpendicular lines always form a 90-degree angle.
True.
How many degrees is a straight angle?
180.
An angle measures 130 degrees. Is that closer to a quarter turn or a half turn?
A half turn (180 degrees).
Name all three types of angles we learned. Give one example degree measure for each.
Acute (less than 90)
right (exactly 90)
obtuse (more than 90, less than 180)
What do angles on a straight line always add up to?
180 degrees.
Draw two perpendicular line segments in your mind. What angle is formed where they cross?
A right angle (90 degrees)