Reflex Angle

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

Method 01
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

Example 01

(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
= 225

Hence 225 is the value of reflex angle

Method 02
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

Example 01
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

Hence
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?

Read Solution

It is more than 180 but less than 360 degree

(02) Is 180 degree part of reflex angle ?

(03) How to draw reflex angle?

(04) What is complete angle? Is it same as reflex angle?

(05) What are other types of angles other than reflex angle?

Read Solution