---

fun rectangleArea(width: Double, height: Double = width): Double {
    return width * height
}

fun circleArea(radius: Double, pi: Double = Math.PI): Double {
    return pi * radius * radius
}

fun triangleArea(a: Double, b: Double, c: Double): Double {
    val p = (a + b + c) / 2
    return Math.sqrt(p * (p - a) * (p - b) * (p - c))
}

fun totalPerimeter(vararg sides: Double): Double {
    var total = 0.0

    for (side in sides) {
        total = total + side
    }

    return total
}

fun main() {
    println("Прямоугольник: ${rectangleArea(5.0, 4.0)}")
    println("Квадрат: ${rectangleArea(width = 5.0)}")

    println("Круг: ${circleArea(3.0)}")
    println("Круг: ${circleArea(radius = 3.0, pi = 3.14)}")

    println("Треугольник: ${triangleArea(3.0, 4.0, 5.0)}")
    println("Треугольник: ${triangleArea(a = 5.0, b = 5.0, c = 6.0)}")

    println("Периметр: ${totalPerimeter(3.0, 4.0, 5.0)}")
    println("Периметр: ${totalPerimeter(sides = doubleArrayOf(2.0, 2.0, 2.0, 2.0))}")
}