#includevoid main(){ double x,t=-1,i,cos=1,fz=1,fm=1; printf("Input X:"); scanf("%lf",&x); for(i=2;i<=18;i+=2) { fz*=x*x; fm*=(i-1)*i; cos+=t*fz/fm; t=-t; } printf("cos(%lf)=%lf\n",x,cos);}
