 How are you all today? Let us discuss the following question. It says, let you eat a set of all Triangles in a plane if a is the set of all triangles with at least one Angle different from 60 degrees. What is a compliment? So let us draw a figure That will make us understand this question more clear Then this be the universal set that is a set of all the triangles in the plane Now they are talking about Triangles Named as per their measurement. So we have three types of triangles in that we have Equilateral triangle we have right angles triangle 90 degrees here Each angle is measuring 60 degree here one of the angle has to be 90 degrees and then we have an obtuse angled Triangle this is also known as acute angle triangle because all the Angles are acute angle. So this is an obtuse angled triangle So it is saying that set A is the set of all triangles with at least one angle different from 60 degree So here there is a possibility that one of its angle a possibility We have one angle which is different from 60 degree. That is 90 degrees right and here it is an obtuse angle triangle So one of its angle is more than 90 degree and less than 180 degree that is for sure So it is saying that let these two Triangles These two type of triangles We named as set A. So what will be a Complement it's obvious that A complement will be the triangle which is not included in set A and Which is there in the universal set and hence it is the set of all the Equilateral triangle. So simply we can write our answer as set of all Equilateral Triangles Complement right. So this was just an example to make This question more clearer to you. I hope you enjoyed the session Bye