View Compilation Error

0_0_38919466_26648.cpp:6:27: error: 'sqrt' was not declared in this scope
    6 | const double sTwo = 1.0 / sqrt(2.0); //斜向前进一步，在X轴和Y轴上移动的距离
      |                           ^~~~
0_0_38919466_26648.cpp: In function 'int main()':
0_0_38919466_26648.cpp:83:46: error: 'sqrt' was not declared in this scope
   83 |                                 double dis = sqrt(x * x + y * y); //距离
      |                                              ^~~~