fn main() {
    const EARTH_RADIUS_IN_KM: f64 = 6371.0;

    let kcle_latitude_degrees: f64 = 41.4075;
    let kcle_longitude_degrees: f64 = -81.851111;

    let kslc_latitude_degrees: f64 = 40.7861;
    let kslc_longitude_degrees: f64 = -111.9822;

    let kcle_latitude_radians = kcle_latitude_degrees.to_radians();
    let kslc_latitude_radians = kslc_latitude_degrees.to_radians();

    let delta_latitude = (kcle_latitude_degrees - kslc_latitude_degrees).to_radians();
    let delta_longitude = (kcle_longitude_degrees - kslc_longitude_degrees).to_radians();

    let inner_city_angle = f64::powi((delta_latitude / 2.0).sin(), 2)
        + kcle_latitude_radians.cos()
            * kslc_latitude_radians.cos()
            * f64::powi((delta_longitude / 2.0).sin(), 2);

    let inner_city_angle = 2.0 * inner_city_angle.sqrt().asin();
    let distance = inner_city_angle * EARTH_RADIUS_IN_KM;

    println!(
        "The distance between the two points is {:.1} kilometers",
        distance
    )
}