Is a decagon a regular polygon?

Answer 1

ofcourse no, quadrilateral means its a poligon with 4 sizes, like square, rectangle, rhombus, trapezium, etc... And Decagon, means its a poligon with 10 sizes. a decagon is a polygon with ten sides. a quadrilateral is a polygon with four sides. "deca" = 10 "quadri" = 4

Answer 2

The term decagon just means a 10 sided polygon. If the angles are all the same then it is regular. You have draw one that is regular and one that is not.