View Compilation Error

0_0_21798991_10130.cpp:72:45: error: 'Poi' does not name a type
 double LineCrossCircle(const Point &a,const Poi
                                             ^
0_0_21798991_10130.cpp:72:45: error: expected ',' or '...' at end of input
0_0_21798991_10130.cpp:72:45: error: expected ')' at end of input
0_0_21798991_10130.cpp:72:45: error: expected initializer at end of input