根据题意可得代码如下:
#include #include const double pi=3.14159265;int main(){ double a, b, C, c; printf ("请输入两边长度及其夹角(角度):"); scanf ("%lf%lf%lf", &a, &b, &C); c = sqrt(a*a+b*b-2*a*b*cos(C*pi/180)); printf ("第三边的长度为:%f\n", c); return 0;}