console.log("Задание 1 ----------");
let hello = "Hello world!";
let message;
message = hello;
console.log(hello, message);

console.log("Задание 2 ----------");
function auto(x1, x2, s1, t) {
  let speed = x1 + x2;
  let s2 = speed * t;
  let endS = s1 - s2;
  if (endS < 0) {
    return -endS;
  }
  return endS;
}
console.log(auto(5, 5, 50, 6));

console.log("Задание 3.1 ----------");
function f3(a, b) {
  if (a < b) {
    return a + b;
  }
  if (a > b) {
    return a - b;
  }
  return a * b;
}
console.log(f3(1,2));
console.log(f3(2,1));
console.log(f3(2,2));

console.log("Задание 3.2 ----------");
function f3_2(num) {
  switch(num) {
  case 1:
    return "зима"
  case 2:
    return "весна"
  case 3:
    return "лето"
  case 4:
    return "осень"
  default:
    return "Кто ты такой?"
  }
}
console.log(f3_2(1));
console.log(f3_2(2));
console.log(f3_2(3));
console.log(f3_2(4));
console.log(f3_2(5));

console.log("Задание 4.1 ----------");
for (var i = 1; i <= 100; i++) {
  console.log(i);
}
console.log("Задание 4.2 ----------");
for (var i = 11; i <= 33; i++) {
  console.log(i);
}
console.log("Задание 4.2 ----------");
let sum = 0;
for (var i = 1; i <= 100; i++) {
  sum += i;
}
console.log(sum);

console.log("Задание 5 ----------");
function f5(s) {
  return s === s.split("").reverse().join("")
}
console.log(f5("hello"));
console.log(f5("ollo"));

console.log("Задание 6 ----------");
function len(s1, s2) {
  return s1.length + s2.length
}
console.log(len("hello", "world"));

console.log("Задание 7.1 ----------");
console.log([1,2,3].concat([4,5,6]));
console.log("Задание 7.2 ----------");
console.log([1,2,3].reverse());
console.log("Задание 7.3 ----------");
let arr7_3 = [1,2,3]
arr7_3.push(4,5,6)
console.log(arr7_3);
console.log("Задание 7.4 ----------");
let arr7_4 = [1,2,3]
arr7_4.unshift(4,5,6)
console.log(arr7_4);
console.log("Задание 7.5 ----------");
console.log(['js', 'css', 'jq'][0]);
console.log("Задание 7.6 ----------");
let arr7_6 = ['js', 'css', 'jq']
let last = arr7_6[arr7_6.length - 1]
console.log(last);
console.log("Задание 7.7 ----------");
let arr7_7 = [1,2,3,4,5]
let a7_7 = arr7_7.slice(0,3)
console.log(a7_7);
let b7_7 = arr7_7.slice(3,5)
console.log(b7_7);
console.log("Задание 7.8 ----------");
let arr7_8_1 = [1,2,3,4,5]
arr7_8_1.splice(1, 2)
console.log(arr7_8_1);
let arr7_8_2 = [1,2,3,4,5]
arr7_8_2.splice(5, 0, 2, 3, 4)
console.log(arr7_8_2);
console.log("Задание 7.9 ----------");
console.log([3, 4, 1, 2, 7].sort());

console.log("Задание 8.1 ----------");
function f8_1(a, b) {
  return Math.pow(a, b);
}
console.log(f8_1(2,3));
console.log("Задание 8.2 ----------");
function f8_2(a, b, round) {
  return a * b * Math.sin(round / 180 * Math.PI) / 2;
}
console.log(f8_2(2, 3, 90));