Code shared from the Rust Playground

playground.rs

//! this script recreates the book
//! "It's not a sin: An Introduction to the Trigonometric Values of Standard Functions"
extern crate rand; // 0.8.4;
use rand::prelude::*;
const DEGREES_RANGE: std::ops::RangeInclusive<i16> = -2000..=2000;
const NUMBER_QUESTIONS: i16 = 20; // questions per function. 250 in the book
fn main() {
    let mut rng = thread_rng();
    let functions: Vec<(&str, fn(f64) -> f64)> =
        vec![("sin", f64::sin), ("cos", f64::cos), ("tan", f64::tan)];
    for f in functions {
        println!("{:?} questions\n{}\n", f.0, "-".repeat(80));
        for q in 1..=NUMBER_QUESTIONS {
            let deg = rng.gen_range(DEGREES_RANGE);
            println!(
                "Question {}. Which of these is closest to the value of {}({}º)?",
                q, f.0, deg
            );
            let right_answer = f.1((deg as f64).to_radians());
            let mut a = vec![format!("{:.2}", right_answer)];
            for _ in 0..5 {
                a.push(format![
                    "{:.2}",
                    f.1((rng.gen_range(DEGREES_RANGE) as f64).to_radians())
                ]);
            }
            a.shuffle(&mut rng);
            println!(
                "A. {}\nB. {}\nC. {}\nD. {}\nE. {}\nF. {}",
                a[0], a[1], a[2], a[3], a[4], a[5]
            );
            println!(
                "Answer {}. {}({}º) is approximately equal to {:.2}\n",
                q, f.0, deg, right_answer
            );
        }
    }
}