Angle names
Acute angle
Web animation
An acute angle is between 0 and 90 degrees
Angle names
Obtuse angle
An obtuse angle is between 90 and 180 degrees
Website animation
Angle names
Reflex angle
A reflex angle is between 180 and 360 degrees
Angle names
Right angle
A right angle is 90 degrees
Angle names
Right angle
A right angle is 90 degrees
Angle names
Straight angle
A straight line is 180 degrees
Guessing the angle size
• The clock is divided into 12 hours.
• One complete circle is 360 degrees.
• Each hour makes 30 degrees.
What angle do the hands of the clock make?
• 4 lots of 30 degrees.• 120 degrees.• OR the reflex angle
is 240 degrees.
Complementary angles
• Two angles which add up to 90 degrees are said to be complementary.
Complementary angles
• What is the complement of 58 degrees?
?
Complementary angles
• What is the complement of 45 degrees?
?
?
Supplementary angles
• Two angles which add up to 180 degrees are said to be supplementary.
Supplementary angles
• What is the supplement of 120 degrees?
?
?
Supplementary angles
• What is the supplement of 40 degrees?
?
Supplementary angles
• What is the supplement of 140 degrees?
Measuring angles
• We use a protractor to measure angles.
There are two scales marked on your protractor
First decide if your angle is acute or obtuse
This angle is acute
The angle is 124 degrees.