vertices in geometry

Geometry is one of the most important branches of mathematics and in the domain of geometry; a vertex is just a corner or a point where more than one edges, lines or curves meet. In simple words, the meeting point of lines is known as the vertex. Vertex is the singular form, and more than one vertex is called vertices, which is a plural form. Example of a vertex is just a point where the endpoints of two lines are together. An angle has only one vertex as the corner consists of a point, which is the intersection of two lines. In case of a pentagon, there is a total of 5 points where five lines are together pairwise forming more than one vertex; hence, a pentagon has five vertices. The same theory goes for every other type of polygon, high-dimensional polytope and polyhedron, which have more than one faces, edges, lines intersecting together. In solid geometry, such as a cube, the intersection of three lines form a vertex, and eight vertices together form the whole cube.

different ways of identifying them

There are several ways to find vertices in geometry. Numerous functions of mathematics have the use of vertices. The use of vertices can be found in the application of polyhedrons, quadratic equations and parabolas, inequalities in systems, which can have one or more vertices. Depending on the different scenarios and situations, the ways of vertex finding are different. The following section is a detailed discussion about the most common and popular ways to find vertices in real-life situations.

Vertex finding in Polyhedron: One of the most important formula in the field of geometry is the formula of Euler. When the formula is written as a form of an equation, it looks like F + V – E = 2.  Here in the equation, the term F is referring to the total number of faces, V is referring to the number of corner points or the vertices and finally, the term E is referring to the total of number of edges. The formula is applicable to the graphs and other polyhedrons with the states where the object is not intersecting itself. As the formula suggests, number of faces with the addition of number of vertices will always be two when the number of edges is subtracted from the summation. If the equation is already given and all the data is available to solve the equation, the simple way to solve the equation is to rearrange the formula to find the vertex. Finally, to find the vertices, the formula can be written as -

F+V-E = 2

=> F+V-E-F = 2-F

=> V-E+E = 2-F+E

=> V = 2-F+E

Vertex finding in systems of linear inequalities:  In this method, first, we have to draw a graph according to the data given in the equation. When we draw the problem, then all the points of the vertices can be found easily. From the picture, we can easily identify the requirement. There is a chance that if not all the vertices, however, some vertices may lie. If the drawn picture of the equation does not provide the positions of the required vertices, then the vertex has to be found with the method of algebra. The equation is given as-

y < x

y > -x + 4

From the above equations, we have to change the inequalities in to the form of y=x and y=-x+4.

There are a few different ways to solve the equations to find the value of ‘x’ and ‘y’. One method is by putting the value of ‘y’ into the second equation, such as placing the value of the y=x into the second equation. So the second equation becomes x=-x+4. After solving the second equation, the value of x is 2. Now we have to put the found value of x into the first equation. Thus, the value of y is now 2. Here, the value of the coordinate is found as both the values of x and y is found. The coordinate of the vertex is (2, 2) in the graph.

Vertex finding in parabola with symmetry axis: In this type, we have to write the factored form of quadratic equation. There are numerous way to find the factored form of the equation but when the results are out, we will have only two sets of parenthesis. After multiplying them we can have the initial equation. An example is-

3x2 – 6x – 45

=>3(x2 – 2x - 15)

Now we have to multiply the value of terms a and c which is:

1 * -15 = -15

Next step is to find two numbers that have the multiplied value of -15 and a value that is equal to the value of b which is:

-2: 3*-5 = -15; 3-5 =-2

Next the two values have to be substituted in equation:

ax2 + kx + hx + c: 3(x2 + 3x - 5x - 15)

Next step is to group the equation with the help of polynomial factoring:

f(x) = 3 * (x + 3) * (x - 5)

From the above equation, two values of x can be found, which is -3 and 5. Now we have to find out the midway point as the required value lies between these points. The value of the midway point is 1. Now as the value of the x is found, the value can be directly plugged into the first equation for the parabola.

y = 3x2 - 6x - 45

y = 3(1)2 - 6(1) - 45

y = -48

Finally the value of the x and y is found which is the value of the vertex coordinate in the plane which (1, -48). These are the few different ways to find the vertices. Some other methods are vertex finding in parabola by completing the square and with the help of simple formula.