View Compilation Error

0_0_4716831_20799.cpp: In function `int intersect(Circle, Circle, Point&, Point&)':
0_0_4716831_20799.cpp:117: error: `my_my_sqrt' undeclared (first use this function)
0_0_4716831_20799.cpp:117: error: (Each undeclared identifier is reported only once for each function it appears in.)