Angle with measurement between 180 and 360 degree is a Reflex Angle
If you want to draw reflex angle, chose angle from 181 to 359 degrees,
Some examples of Reflex Angle
How to Measure Reflex Angle
Measuring Reflex angle is tricky because the protractor can measure angle only up to 180 degree and the reflex angle starts after 180.
Here we will discuss two method of Reflex Angle Measurement
Direct measurement using protractor
Here the reflex angle is measure in three steps
(a) First measure 180 degree
(b) Then measure the remainder angle
(c) Add both (a) + (b)
Let us understand the method with examples
(a) Measure 180 degree
We know that 180 degree is a straight line.
Just extend the line AB as given in the below image.
From the above image we get;
Angle ABD = 180 degree
Now find angle DBC.
(b) The remainder angle DBC can be measured using protractor
Using the Protractor we found that, Angle DBC= 45 degree
(c) Adding both the angles
= Angle ABD + DBC
= 180 + 45
Hence 225 is the value of reflex angle
Indirect angle calculation
This method involves two steps
(a) Measure the outer angle
(b) Subtract the angle from 360 degree
Let us understand this with example
Find the reflex angle ABC (marked in blue arrow)
Do the following steps
(a) Measure the outer angle using protractor
The outer angle is marked in Green Arrow
Measuring it with protractor we get:
Outer angle = 135 degree
(b) We know that angle of full rotation = 360 degree
Subtract, 360 – 135 = 225 to get the desired angle value
Angle ABC = 225 degree
I hope both the method is clear.
I know that the technique is tricky but with sufficient practice you will get it.
Reflex Angle in Real Life
(a) Clock showing 8 PM
(b) Yoga Posture
(c) One slice eaten pizza
Important Questions on Reflex Angle
(01) what is the angle in Reflex Angle?
It is more than 180 but less than 360 degree
(02) Is 180 degree part of reflex angle ?Read Solution
No, Angle above 180 degree comes under reflex angle
(03) How to draw reflex angle?
The method involve two steps:
(a) First draw 180 degree straight line
(b) Then draw remainder angle using protractor
(04) What is complete angle? Is it same as reflex angle?Read Solution
A 360 degree angle is known as compete angle
No, its different than reflex angle as the reflex angle measure is less than 360 degree
(05) What are other types of angles other than reflex angle?
Other angles are:
Acute angle, Right Angle, Obtuse Angle, straight angle and full rotation