Two-dimensional geometric shapes

Triangle

Keywords: Triangle

Area of a Triangle

Area of a triangle with height

A=aha2=bhb2=chc2
A=absinγ2=bcsinα2=casinβ2

Area of a triangle - Heron's formula

A=s(sa)(sb)(sc), s=a+b+c2

Area of a triangle using coordinates of points

A ( x 1 , y 1 ) ,     B ( x 2 , y 2 ) ,     C ( x 3 , y 3 )
A=12x1(y2y3)+x2(y3y1)+x3(y1y2)

or using a determinant

A=12|x1y11x2y21x3y31|

INCIRCLE AND EXCIRCLES OF A TRIANGLE

Incircle and excircles of a triangle

Areao of triangel using radius of excircle

A=a·b·c4R

Areao of triangel using radius of incircle

A=s·r