---

import kotlin.math.sqrt

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 sqrt(p * (p - a) * (p - b) * (p - c))
}

fun totalPerimeter(vararg sides: Double): Double {
    return sides.sum()
}


fun main() {

    println("Прямоугольник:")
    println(rectangleArea(5.0, 10.0))
    println(rectangleArea(width = 7.0))

    println("\nКруг:")
    println(circleArea(5.0))
    println(circleArea(radius = 3.0, pi = 3.14))

    println("\nТреугольник:")
    println(triangleArea(3.0, 4.0, 5.0))
    println(triangleArea(a = 5.0, b = 5.0, c = 6.0))

    println("\nПериметр:")
    println(totalPerimeter(5.0, 5.0, 5.0))
    println(totalPerimeter(3.0,4.0,5.0))
}