The Quadrilaterals part 1

Quadrilateral is a plane figure (polygon) with four sides and four vertices. It is also called tetragon and quadrangle. While in triangle, the sum of the interior angles is 180° ; for the quadrilaterals the sum of the interior angles is always equal to 360° A + B + C + D = 360° Classifications of Quadrilaterals Simple - sides of simple...

Formulas: Radius of Inscribed and Circumscribed Circle in a Triangle

One of the common word problems in plane geometry is finding either the radius of the inscribed circle or the radius of circumscribed circle in a triangle. Familiarize yourself with the different formulas of finding the radius according to the kind of triangles involved. The efficiency of getting the correct solutions for every problems is...

Derivation of Formula for the Radius of Circumcircle

Most of the Plane Geometry problems in triangle could be easy solve by direct substitution using the applicable formula according to the given value of the problems. To find the radius of the circumscribed circle (circumcircle) given the value of the area and the three sides, simply divide the product of the three sides by 4 times the area...

Derivation of Formula for the Radius of Incircle

Most of the Plane Geometry problems in triangle could be easy solve by direct substitution using the applicable formula according to the given value of the problems. To find the radius of the inscribed circle (incircle) given the value of the area and the three sides, simply divide the area by the half of the perimeter (s). In other words,...

Special Centers in a Triangle

Centroid Centroid is the point of intersection of all the medians of a triangle. It is the geometric of a plane figure. Incenter Incenter is the point of intersection of all angle bisectors in a triangle. It is also the center of the inscribed circle (incircle) in a triangle. where A = area of the triangle and s = ½ (a + b + c). ...

Special Lines in a Triangle

Side Side of a triangle is a line segment that connects two vertices. Triangle has three sides. Vertex Vertex is the point of intersection of two sides of triangle. Median, m A median of a triangle is a segment from vertex to the midpoint of the opposite side. A triangle has three medians, and these three will intersect at the centroid....

Mensuration Formulas of the Triangles

Definition of a Triangle Triangle is a polygon with three sides and three vertices. It can also be defined as closed figure bounded by three straight lines called sides. If three sides of a triangle are equal, it is an equilateral triangle. An equilateral triangle is also equiangular. It two sides are equal, it is an isosceles triangle....