Triangle

A triangle is a polygon with three sides, three vertices, and three angles.  The sum of the interior angles of any triangle is always 180 degrees.

• All triangles have three angles.
• All triangles have three sides.
• The sum of all angles of a triangle always equal \(180^\circ\).     \( x^\circ \;+\; y^\circ \;+\; z^\circ = 180^\circ  \)
• Sides:  \(a\),  \(b\),  \(c\)
• Angles:  \(A\),  \(B\),  \(C\)
• Height:  \(h_a\),  \(h_b\),  \(h_c\)
• Median:  \(m_a\),  \(m_b\),  \(m_c\)  -  A line segment from a vertex (corner point) to the midpoint of the opposite side
• Angle bisectors:  \(t_a\),  \(t_b\),  \(t_c\)  -  A line that splits an angle into two equal angles
• Perimeter:  \(P\)
• Semi-perimeter:  \(s\)  -  One half of the perimeter
• Area:  \(K\)
• Inradius of triangle:  \(r\)
• Outradius (circumcircle) of triangle:  \(R\)  

• Tags: Triangle

Triangle Index

• Right Isosceles Triangle
• Right Triangle
• Equilateral Triangle
• Isosceles Triangle
• Acute Triangle
• Obtuse Triangle
• Scalene Triangle

 

Right Isosceles Triangle

• One side of a right isosceles triangle is 90° and two angles are equal.

 

 

 

 

 

 

 Right Triangle

• One side of a right triangle is 90°, the other two angles are unequal and no sides are equal.

 

 

 

 

 

 

Equilateral Triangle

• An equilateral triangle is when all three angles are equal.
• A equilateral triangle is a polygon.

 

 

 

 

 

Isosceles Triangle

• An isosceles triangle is when two sides are equal and two angles are equal.

 

 

 

 

 

 

Acute Triangle

• An acute triangle is when all three angles of the triangle are less than right angles.
• An acute triangle is a oblique triangle.

 

 

 

 

 

Obtuse Triangle

• An obtuse triangle is when one of the three angles is greater than a right angle.
• An obtuse triangle is a oblique triangle.

 

 

 

 

 

 Scalene Triangle

• An scalene triangle is when no sides and angles are equal.