Angles in Grade VII

Students, today I will make you aware with geometry of Grade VII. Before we move to any topic or any other things tell me what is geometry? Geometry is any well defined shape; each solid object has its own geometry that describes its shapes, properties, etc. Geometry is all about shapes, if you get familiar with shapes then you are the hero of geometry. as you study algebra from primary grades similarly you will also learn geometry from primary schools. As you grow up and grade changes complexity of topics also changes.

Today we are going to talk about Complementary and supplementary angles. First go through complementary angle. Two angles are called as complementary if the sum of their angles is equal to 90⁰. If one angle is known, than its complementary angle can easily be determined by subtracting the measure of its angle from 90⁰.   

For instance: What is the complementary angle of 47^o? 
Solution: 90^o  -  47^o  =  43^o

Whenever we have to determine the complementary angle and one is given minus it from 90 and the resultant angle is determined in this way.

Example 2: if we have two angles as 27⁰ and 63⁰, are they complementary angles or not.

Answer: we have two angles,

One is 27, and other is 63,

If we add both the angles then they will give result as: 27 + 63 = 90,

Hence it is a complementary angle, as sum of both the angles is equal to 90 which is the condition of complementary angle.  

 

Now, the other type of angle i.e. called as the supplementary angle, if the sum of two angles is equal to 180 then such kind of angles are named as Supplementary angles. When one angle is unknown to you and you have to determine the unknown one then you can easily calculate it by subtracting the given angle from 180⁰.

Let’s see how to calculate the unknown angle with help of example.

Determine the second supplementary angle when one is 143^o? 
Answer: 180^o  -  143^o  =  37^o

Now the other example of the same, calculate that the given angles form a supplementary angle or not?

 Suppose you have two angles, 100⁰ and 80⁰,

You can easily say that both angles results, supplementary angle. Because when we add them they will give result as:

100⁰ + 80⁰ = 180⁰

Thus, satisfying the condition of the supplementary angle.

Example: one angle is 24⁰ and other is 58⁰  tell whether it is complementary or supplementary angle.

Solution: Angle one = 24⁰, second angle = 58⁰,

first + second = 24⁰ + 58⁰,

                            = 82⁰.

As on adding both angles we are getting only 82, so it is neither a complementary angle nor supplementary. Because for complementary angle it must be equal to 90⁰ and for supplementary it must be 180⁰.
In the upcoming article we will talk about other topics of geometry and if you have any doubt than you can take my help easily. I am here to help you and to solve your mathematical problems.