- 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 (coiner 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: \(R\)
Types of Triangles
Right Isosceles Triangle
- One side of a right isosceles triangle is 90° and two angles are equal.
- One side of a right triangle is 90°, the other two angles are unequal and no sides are equal.
- An equilateral triangle is when all three angles are equal.
- A equilateral triangle is a polygon.
- An isosceles triangle is when two sides are equal and two angles are equal.
- An acute triangle is when all three angles of the triangle are less than right angles.
- An acute triangle is a oblique triangle.
- An obtuse triangle is when one of the three angles is greater than a right angle.
- An obtuse triangle is a oblique triangle.
- An scalene triangle is when no sides and angles are equal.
Tags: Equations for Triangle