...已知三角形的两边a,b及其夹角jc的值,求第三边(a,b,jc由键盘输入)帮 ...答:include <stdio.h> include <math.h> define pi 3.14159265 main(){ float a,b,jc,c;printf("a=");scanf("%f",&a);printf("b=");scanf("%f",&b);printf("jc=");scanf("%f",&jc);/*余弦公式 c*c=a*a+b*b-2*a*b*cos(jc),jc为弧度制*/ c=sqrt(a*a+b*b-2*a*...