c++(函数，余弦)没有给出正确答案

我一个月前才开始学这门c++课程。现在我要写一个程序来计算这个。我不知道我做错了什么。

#include <stdio.h>
#include <math.h>
float gatherl1();
float gatherl2();
float gatheran();
void values(float,float,float);
float findlength(float,float,float);
float findan2(float,float,float);
float findan3(float,float,float);
void name(float,float,float);

int main(void)
{ 
    float length1,length2;
    float length3;
    float angle1,angle2,angle3;
    length1 = gatherl1();
    length2 = gatherl2();
    angle1 = gatheran();
    values(length1,length2,angle1);
    length3 = findlength(length1,length2,angle1);
    angle2 = findan2(length1,length2,length3);
    angle3 = findan3(length1,length2,length3);
    name(angle1,angle2,angle3);
}
float gatherl1()
{
        float l1;
        printf("Enter the length of one of the sides of any trianglen");
        scanf("%f",&l1);
        return l1;
}
float gatherl2()
{
        float l2;

        printf("Enter the length of the other siden");
        scanf("%f",&l2);

        return l2;
}
float gatheran()
{
        float angle;
        printf("Enter the angle between them.n");
        scanf("%f",&angle);
        return angle;
}

void values(float l1, float l2, float angle)
{
    printf("n The two sides are %f and %f. The angle between them is %f n",l1,l2,angle);
}
float findlength(float l1, float l2, float angle)
{
    float l3,pyt,boy;
    if (angle==90)
    {
        pyt = pow(l1,2) + pow(l2,2);
        l3 = sqrt(pyt);
    }
    else 
    {
        boy = pow(l1,2) + pow(l2,2) - 2*l1*l2*cos(angle);
        l3 = sqrt(boy);
    }

    printf("nthe third side is = %f",l3);
    return l3;
}
float findan2(float l1, float l2, float l3)
{
    float cosangle2,angle2;
    cosangle2 = (pow(l2,2) + pow(l3,2) - pow(l1,2)) / (2*l2*l3);
    angle2 = acos(cosangle2);
    return angle2;
}
float findan3(float l1, float l2, float l3)
{
    float cosangle3,angle3;
    cosangle3 = (pow(l1,2) + pow(l3,2) - pow(l2,2)) / (2*l1*l3);
    angle3 = acos(cosangle3);
    return angle3;
}
void name(angle,angle2,angle3)
{
    printf("nnn the other two angles are %f and %f",angle2,angle3);
    printf("nnn The angle you put is %f",angle);

    if(angle == 90)
    {
        printf("n The triangle is a right trianglen");
    }
    else if(angle < 90)
    {
        printf("n The triangle is a acute trianglen");
    }
    else
    { 
        printf("n The triangle is a obtuse trianglen");
    }

}

我以前从未使用过cos和arccos函数，所以我不确定这是否是原因。或者是函数，因为我对函数也不熟悉。请救救我!!谢谢你。