Javascript: 3 functions that calculates the area of a triangle, circle, or rectangle returns undefined

Sorry for this very simple question but I can't seem to narrow down why the following functions return "undefined" for all results. This is my code:

function calculateTriangleArea(x, y){
  x * y / 2 
}
function calculateRectangleArea(x, y){
  x * y
}
function calculateCircleArea(x){
  Math.PI * x * x
}

if (calculateRectangleArea.name === true)
 (function calculateRectangleArea(x, y)
  {return [x * y]
})
if (calculateTriangleArea.name === true)
  (function calculateTriangleArea(x, y){
   return[x * y / 2]
})

else (function calculateCircleArea(x){
  return [Math.PI * x * x]
})

when i run these 9 console.log commands it all returns undefined.

console.log(calculateRectangleArea(10, 5));     // should print 50
console.log(calculateRectangleArea(1.5, 2.5));  // should print 3.75
console.log(calculateRectangleArea(10, -5));    // should print undefined
console.log(calculateTriangleArea(10, 5)); // should print 25
console.log(calculateTriangleArea(3, 2.5)); // should print 3.75
console.log(calculateTriangleArea(10, -5)); // should print undefined
console.log(calculateCircleArea(10)); // should print 314.159...
console.log(calculateCircleArea(3.5)); // should print 38.484...
console.log(calculateCircleArea(-1)); // should print undefined