Triangle a

Type Function

Input S1	REAL (side 1)
A	REAL (angles between page 1 and page 2)
S2	REAL (side length 2)
S3	REAL (side length 3)
Output	REAL (area of the triangle)
	TRIANGLE_A calculates the area of any triangle. The triangle can be defined by either through 2 pages and the pages spanned by the angles 1 and 2 (S1, S2 and A), or if A = 0 then the area is calculated from three sides (S1, S2 and S3).