Poj 1673 exocenter of a triangle (Triangle center Center)

Exocenter of a triangle Time limit:1000 ms   Memory limit:10000 K Total submissions:2947   Accepted:1116 Description Given a Triangle ABC, The extriangles of ABC are constructed as follows: On each side of ABC, construct a square (abde, bchj and acfg in the figure below ). Connect adjacent square corners to form the three extriangles (AGD, bej and CFH in the figure ). The exomedians of ABC are the medians of the extriangles, which pass through vertices of the original triangle, extended into the original triangle (Lao, MBO and NCO in the figure. as the figure indicates, the three exomedians intersect at a common point called The exocenter (point O in the figure ). This problem is to write a program to compute the exocenters of triangles. Input The first line of the input consists of a positive integer N, which is the number of datasets that follow. each dataset consists of 3 lines; each line contains two floating point values which represent the (two-dimeneting) Coordinate of one vertex of a triangle. So, there are total of (N * 3) + 1 lines of input. note: All input triangles wi ll be strongly non-degenerate in that no vertex will be within one unit of the line through the other two vertices. Output For each dataset you must print out the coordinates of the exocenter of the input triangle correct to four decimal places. Sample Input 20.0 0.09.0 12.014.0 0.03.0 2.16192.162.0-10.0 Sample output 9.0000 3.7500-48.0400 23.3600 Source Greater New York 2003

Question: http://poj.org/problem? Id = 1673

Question: give you a triangle, draw various pictures, give a new definition, and finally convert it into a question of looking down

Analysis: triangle center, enumeration of two sides, can calculate the pole angle perpendicular to them, and then list the two equations to solve the problem, directly copyCodeJust do

PS: This question is quite disgusting. Fortunately, poj has discuss and takes a glance at it. The answer is to add an EPS to AC =

Code:

 # include 
  
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     # include 
    
      using namespace STD; double ax, ay, BX, by, CX, Cy, R, A1, A2, X, Y; int N; int main () {scanf ("% d", & N); While (n --) {scanf ("% lf", & ax, & ay, & BX, & by, & CX, & CY ); a1 = atan2 (by-ay, Bx-Ax) + ACOs (-1.0)/2; a2 = atan2 (Cy-by, CX-bx) + ACOs (-1.0) /2; r = (sin (A2) * (CX-Ax) + cos (A2) * (Ay-cy)/(sin (A1) * Cos (A2) -Sin (A2) * Cos (A1); X = cx + R * Cos (A1), Y = Cy + R * sin (A1); printf ("%. 4lf %. 4lf \ n ", x + 1e-8, Y + 1e-8);} return 0 ;}