View Compilation Error

0_0_32999785_7197.cpp: In function 'int main()':
0_0_32999785_7197.cpp:20:22: error: 'sin' was not declared in this scope
        b=0.5*sin(jiao)*r*r;
                      ^
0_0_32999785_7197.cpp:26:31: error: 'setprecision' was not declared in this scope
    cout<<fixed<<setprecision(3)<<d<<endl;
                               ^