I really don't think there is need to work this out mathematically. It would just look unnatural. Daffodils are asymmetrical on their stems and will sometimes turn towards the light so they don't lend themselves to rows or geometric arrangements. 50 daffodils will not stretch very far in that space, even at 6 inches apart, which is quite a big distance. I'd just put them in groups of around 10, 4 inches or so apart, and spread the 5 groups out by eye. Smaller groups or singles would just look spotty imo.

If the area has 4 sides as you have described, then it is not a triangle :-) It is a trapezoid and there are various online sites that explain how to calculate the area of a trapezoid (and all sorts of other geometric shapes). FYI, the area of your planting bed is 24 square feet or 3456 square inches. This area will accommodate about 110 bulbs at the 6" spacing

But I agree completely with floral that a random placement of your 50 bulbs in clusters of at least 5 bulbs (I prefer the 10 also) will be aesthetically more pleasing than lining them out precisely. Fill in the empty areas with perennials in spring as you desire. And look for perennials that produce a lot of early leafy foliage to disguise the bulb foliage as it ripens in place.

2 easy formulas to remember:

Square or rectangle: A = LxW

Triangle (which is half of a square or rectangle): A = (LxW) x 0.5. Note that one of these numbers (whether you think of it as the length or the width) should be the length of the line that is dropped from one vertex to the opposite side, and be roughly 90-degrees to it (for your estimates, which did not need to be exact)

While you do not describe a true triangle, for your estimating purposes, you can think of it like a triangle. For example, gardengal's number is 24 square feet but estimating without thinking of the fourth side, you get 24 square feet also, and so have the same number for square inches as mentioned above. You can get the inches by using 72 inches instead of 6 feet, and 96 inches instead of 8 feet.

I would like to think all of you for your help and it was a big help in my case for I am a caregiver for my wife that has ALS and at times I do not have the time to do thing.

I have put the bulbs in that area and made 9 holes with some of them having 5 to 6 bulbs in them.

I really hope that it will look as nice as you all say it will.

Thank-You again for all your help.