General triangles
(1). The size of the type: S=AH/2
(2). Three-side a,b,c known triangular, then (Helen Formula) (p= (A+B+C)/2)
S=√[p (P-A) (p-b) (P-C)]
(3). The triangle is known to be a A, B, both sides of the angle C, then S=1/2 * Absinc This can be converted to the vector cross-multiplication formula;
The mixed product of a vector is the volume of a parallelepiped consisting of three vectors. The cross-multiplication can be regarded as the volume of the parallelepiped with a unit length, i.e. the area of its parallelogram
(4). Triangle Triangular Three sides are a, B, c, inscribed circle RADIUS r
S= (a+b+c) R/2
(5). Triangle Triangular Three sides are a, B, C, circumscribed circle radius r
s=abc/4r
(6). Calculate area according to trigonometric functions:
s= ABSINC/2 A/SINA=B/SINB=C/SINC=2R
Note: where R is the tangential circle radius.
Triangle Area Formula