View Compilation Error

0_0_12835922_9142.cpp:7: error: `acos' was not declared in this scope
0_0_12835922_9142.cpp: In function `double dist(point, point)':
0_0_12835922_9142.cpp:26: error: expected primary-expression before "double"
0_0_12835922_9142.cpp:26: error: expected `;' before "double"
0_0_12835922_9142.cpp:26: error: expected `}' at end of input