really simple code with wrong results

#include <iostream>
#include <math.h>
using namespace std;

double calcAcceleration(double theta);

int main()
{
    double theta=23.5;
    cout<<"A child on a sleigh is travelling down a frictionless hill with a slope of 23.5 degrees, it is accelerating at a constant rate of: ";
    cout<<calcAcceleration(theta);
    cout<<"m/s^2.\n";
    cout<<"Let's hope that isn't a very high hill.\n";
    return 0;
}

double calcAcceleration(double theta)
{
    double radians = theta/180;
    double a = (9.8*(sin(radians)));
    return a;
}