A relation is a function if no pair of the relation has the same first elements. On the graph,two points will lie in the same vertical line if and only if the first coordinate of the two points are same. Therefore if a vertical line intesect the Relation graph at two points then it is not a function. This is called the Vertical line test. If all vertical lines intersect a curve at most once then the curve represents a function

Complex numbers are the numbers of the form a+ib where a and b are real numbers.

Definition:- Complex numbers are defined as an ordered pair of real numbers like (x,y) where

z=(x,y)=x+iy

and both x and y are real numbers and x is known as real part of complex number and y is known as imaginary part of the complex number.

Area and Perimeter Formula are used to calculate the Area and Perimeter for the plane figure i,.e 2-D figure like Rectangle ,square ,Circle, Quadrilaterals etc. Area and Perimeter Area is the space occupied by the plane Figure Perimeter is the distance around the outside Surface Area and Volume Surface Area and Volume is used for