import?math
combination_list?=?[（0?1?2）?（0?1?3）?（0?1?4）?（0?1?5）?（0?2?3）?（0?2?4）?（0?2?5）?（0?3?4）?（0?3?5）?（0?4?5）?（1?2?3）?（1?2?4）?（1?2?5）?（1?3?4）?（1?3?5）?（1?4?5）?（2?3?4）?（2?3?5）?（2?4?5）?（3?4?5）];
def?solve_quadratic_equation（a?b?c）:
????if?a==0:
????????return?‘二次項不能為零！‘?;
????delta=b*b-4*a*c;
????if?delta>=0?and?a!=0:
????????x1?=?（-b+math.sqrt（delta））/（2*a）;
????????x2?=?（-b-math.sqrt（delta））/（2*a）;
????????return?[x1x2];
????else:
????????return?‘方程無實(shí)數(shù)解！‘?;

def?triangle_area（x1y1x2y2x3y3）:
????return?abs（x1*y2-x2*y1+x3*y1-x1*y3+x2*y3-x3*y2）/2;

def?triangle_perimeter（x1y1x2y2x3y3）:
????a?=?math.sqrt（（x1-x2）**2+（y1-y2）**2）;
????b?=?math.sqrt（（x2-x3）**2+（y2-y3）**2）;
????c?=?math.sqrt（（x3-x1）**2+（y3-y1）**2）;
????return?a+b+c;



‘‘‘
（x1-x）^2+（y1-y）^2=r1^2----①
（x2-x）^2+（y2-y）^2=r2^2----②
①-②==>y=-（x1-x2）/（y1-y2）x+（x1^2-x2^2+y1^2-y2^2+r2^2-r1^2）/2（y1-y2）----③
????????????或x=-（y1-y2）/（x1-x2）y+（y1^2-y2^2+x1^2-x2^2+r2^2-r1^2）/2（x1-x2）----④
當(dāng)x1=/=x2，④代入①，否則③代入①。
‘‘‘
def?circle_intersect（r1r2x1y1x2y2）:
????d?=?math.sqrt（（x1-x2）**2+（y1-y2）**2）;
????if?d>r1+r2:
????????return?‘兩個圓無交點(diǎn)！‘;
????elif??x1!=x2:
????????k=（y1-y2）/（x1-x2）;
????????D=（x1**2-x2**2+y1**2-y2**2+r2**2-r1**2）/（2*（x1-x2））;
????????a=1+k**2;
????????b=（2*k*（x1-D）-2*y1）;
????????c=y1**2+（x1-D）**2-r1**2;
???