Cプログラムで正三角形の内接円の面積を計算します

#include  #include  using namespace std; float area(float a) { if (a < 0 ) //if the value is negative it is invalid return -1; float area = 3.1415 * (a/(2*sqrt(3))) * (a/(2*sqrt(3))); return area; } int main() { float a = 4; cout << "Area is: " << area(a); }

Area is: 4.18867