View Compilation Error

0_0_12157975_16226.cpp: In member function `double Cylinder::getRadius()':
0_0_12157975_16226.cpp:60: error: `sqrt' undeclared (first use this function)
0_0_12157975_16226.cpp:60: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_12157975_16226.cpp: In function `double DistanceSegment3D(Segment3D, Segment3D)':
0_0_12157975_16226.cpp:77: error: `fabs' undeclared (first use this function)
0_0_12157975_16226.cpp:81: error: `sqrt' undeclared (first use this function)