Introduction on how to measure angles learning:

A ruler in the geometry is used to measure the lines and the units used in the rulers are inches or centimeters .In geometry we measure the angles using a tool called the protractor. A protractor uses units called degrees to measure the angles. The protractor measures the angle from left to right. Now we are going to see how to measure the angles and its learning.



How to measure angles learning : types of angles

There are four types of angles. They are acute angles, obtuse angles, right angles and straight angles.

Learning right angles:

The right angles which measures 90 degrees.

                                                                              right angle

Learning straight angles:

The straight angles which measures 180 degrees and it is a straight line.

Learning acute angles:

 An acute angle is an angle which measures less than 90 degrees.

                                                                            acute angle   

Learning obtuse angles:

Obtuse angle is nothing but the measure will be more than 90 degrees and less than 180 degrees.

                                                                            obtuse angle

Learning Supplement angles:


The sum of two angles up to 180 degree is called as the supplement angle.


How to measure angles learning : examples

Now we are going to see about the learning of angles and how to measure with some examples.

Ex 1:

In the given rectangle, what is the type of angle present in the given figure and measure the angles present in it?



In the rectangle all the angles are right angles because it measures 90 degree each in all corners. It consists of four 90 degrees.

Ex 2:

How to find the type of angle present in the triangle, if the measures are 34°, 60°, and 86°?


In a triangle the sum of the measure of three angles are given as,

34° + 60° + 86° = 180°

Thus the angles present in this are acute type of angles.


Ex 3:

Find the supplement of the angle of 47°


The supplementary angle of 47° = 180° – 47° = 133°.

The supplementary angle of 133° = 180° – 47° = 133°.

The angles 47° and 133° are supplementary angles.

Ex 4:

An angle is 20° more than its complement. What is its measure?


                   Let us take the unknown degree as x°

                  Its complement = 90°-x°

                          90°-x°+20°= x°

                                    2x° = 110°

                                      X° = 55°

                   Thus the measure of the angle is 55 degree.