Convex
The term 'Convex' is used to refer to a shape that has a curve or a protruding surface. In other words, all the lines across the outline is straight and they point outwards. Real world objects like a sign board, a football, a circular plate and many more are convex in shape. In geometry there are many shapes that can be classified as convex shapes. For example, a hexagon is a closed polygon with six sides. A hexagon has all its vertices pointing outwards, Also, for a shape to be convex, all the interior angles should be less than 180°. Since a hexagon has all its interior angles less than 180°, it can be named as a convex shape.
1.  Convex Definition 
2.  Convex Polygon 
3.  Concave and Convex Polygons 
4.  Convex Polygon Formulas 
5.  Solved Examples on Convex 
6.  Practice Questions on Convex 
7.  FAQs on Convex 
Convex Definition
Any shape that has a curved surface, and is also closed is defined as 'Convex'. The surfaces of the convex shape or object seem to project outward. In other words, no part of it points inwards. Geometry is a branch of math that deals with lines, points, shapes, solids, In geometry, a shape or a polygon is said to be convex, if the lines connecting them lie completely inside the shape. Every interior angle of a convex polygon is less than 180°.
Convex Polygon
A polygon is a twodimensional shape that has a minimum of three sides and angles. A convex polygon is a shape in which all of its vertices point in the outward direction.
Properties of a Convex Polygon
The following characteristics of a convex polygon helps us to identfy them easily. They are,
 A convex polygon is a polygon where all the interior angles are less than 180º.
 A polygon in which at least one of the angles is greater than 180° is called a concave polygon.
 The diagonals of a convex polygon lie inside the polygon.
 A convex polygon is a polygon where the line joining every two points of it lies completely inside it.
Some examples of convex polygons are as follows:
There are two types of convex polygons. They are regular convex polygons and irregular convex polygons.
Regular Convex Polygon
A regular convex polygon is a polygon where each side is of equal length, and all the interior angles are equivalent and less than 180°. The vertices of the polygon are equidistant from the center of the regular polygon. For example, a regular convex pentagon is an example of a regular convex polygon.
Irregular Convex Polygon
An irregular convex polygon is a polygon where each side is of unequal length, and all the interior angles are of unequal measure. Example: irregular parallelogram is an example of an irregular convex polygon.
Concave and Convex Polygons
Convex and concave shapes are different. The table below shows differences between a convex and concave polygons.
Convex Polygon  Concave Polygon 
The full outline of the convex shape points outwards. i.e., there are no dents.  At least some portion of the concave shape points inwards. i.e., there is a dent. 
All the interior angles of a convex polygon are less than 180°.  At least one interior angle is greater than 180°. 
The line joining any two vertices of the convex shape lies completely in it.  The line joining any two vertices of the concave shape may or may not lie in it. 
Convex Polygon Formulas
A polygon is a shape that has a minimum of three sides and three angles. Every shape occupies some amount of space. This is called as 'Area'. The formulas given below helps to easily find the area, sum of the exterior angles, and sum of the interior angles of a convex polygon.
Area of a Convex Polygon
The space covered inside the boundary of a convex polygon is its area. Considering the coordinates of a convex polygon to be (\(x_{1}\), \(y_{1}\)), (\(x_{2}\), \(y_{2}\)), (\(x_{3}\), \(y_{3}\)), .....(\(x_{n}\), \(y_{n}\)), its area is given by,
Area = 1/2 (\(x_{1}\)\(y_{2}\)  \(x_{2}\)\(y_{1}\)) + (\(x_{2}\)\(y_{3}\)  \(x_{3}\)\(y_{2}\)) + ............ + (\(x_{n}\)\(y_{1}\)  \(x_{1}\)\(y_{n}\))
Sum of Interior Angles
The sum of interior angles of a convex polygon with 'n' sides is given by the formula, 180(n2)°. For example, a hexagon has 6 sides. So the sum of its interior angles is 180(62)°, which is equal to 720°.
Sum of Exterior Angles
The sum of exterior angles of a convex polygon is equal to 360°/n, where 'n' is the number of sides of the polygon.
Think Tank
 Is the sum of interior angles of a concave polygon of n sides 180(n−2) degrees?
 Is the sum of exterior angles of a concave polygon of n sides 360 degrees?
Topics Related to Convex
Check out some interesting articles related to Convex.
 Definition of Polygon
 Polygon Shape
 Similarity in Triangles
 Areas of Similar Triangles
 What is Similarity?
Important Notes
 A polygon is convex if each of its interior angles is less than 180º.
 A polygon is concave if at least one of its interior angles is greater than 180º.
 Parabola is an example of a convex curve.
Solved Examples on Convex

Example 1: What is the measure of an interior angle of a regular pentagon?
Solution:
The number of sides of a pentagon is n =5. We know that the sum of all interior angles of a polygon of n sides is 180(n2)° degrees. Hence, the sum of the interior angles of the pentagon is:
180 × (52)° =180 × (3)°
= 540°
Since the given pentagon is regular, all 5 interior angles measure the same. Therefore, the measure of each interior angle is 540° / 5 = 108°
Therefore, the required angle = 108°. 
Example 2: Find the convex shapes from the following figures.
Solution:
Among the given shapes, (a), (d), and (f) have all their vertices pointing outwards. Also in (a), (d), and (f), all the interior angles measure less than 180°. Therefore, these are the only convex shapes among the given shapes. Therefore, a), d) and f) are convex shapes.

Example 3: Find the area of a regular polygon whose vertices are (6,8), (4.1), and (3, 6).
Solution:
Area of a regular polygon is given by the formula,
Area = 1/2 (\(x_{1}\)\(y_{2}\)  \(x_{2}\)\(y_{1}\)) + (\(x_{2}\)\(y_{3}\)  \(x_{3}\)\(y_{2}\)) + ............ + (\(x_{n}\)\(y_{1}\)  \(x_{1}\)\(y_{n}\))
The vertices are, (\(x_{1}\), \(y_{1}\)) = (6,8) , (\(x_{2}\), \(y_{2}\)) = (4,1) , (\(x_{3}\), \(y_{3}\)) = (3,6)
Substituting the values we get,
Area = 1/2 (6  32) +(24  (3)) + (24  36)
= 1/2 26 + 27  60
= 1/2 59
= 1/2 59
= 59/2 square units
Therefore, the area of the convex polygon is 59/2 square units.
FAQs on Convex
What is Convex?
Convex is used to describe a curved or a bulged outer surface. In geometry, there are many convexshaped polygons like squares, rectangles, triangles, etc.
What is Convex Polygon?
A convex polygon is a shape in which all of its sides are pointing or protruding outwards. No two line segments that form the sides of the polygon point inwards. Also, the interior angles of a convex polygon are always less than 180°.
What is the Sum of Exterior Angles of a Convex Polygon?
The sum of exterior angles of a convex polygon is equal to 360°/n, where 'n' is the number of sides of the polygon.
What is the Sum of Interior Angles of a Convex Polygon?
The sum of interior angles of a convex polygon is equal to (n2) × 180°, where 'n' is the number of sides of the polygon.
Is a Square a Convex Polygon?
A polygon in which all the interior angles are less than 180° is a convex polygon. Also in a square, all the vertices point outwards, which also makes it a convex shape. Therefore, a square is a convex polygon.
Is a Circle Polygon?
A polygon is a figure made up of at least 3 line segments. Since a circle does not have any line segments, we cannot call it a polygon.
What is a Concave Polygon?
A polygon is said to be concave if at least one of its interior angles is greater than 180°. In other words, the vertices of a concave polygon point inwards. A star shape is an example of a concave polygon.