Basic relations between elements of triangle
Area formulas. Heron's formula.
Radii of circumscribed and inscribed circles.
Designations: a , b , c – sides; A , B , C – angles of triangle; p = ( a + b + c ) / 2 - a half-perimeter; h – a height; S – an area; R , r – radii of circumscribed and inscribed circles correspondingly.
Law of cosines:
Law of sines:
Law of tangents:
Area formulas:
Radii of circumscribed and inscribed circles:
