I want to make this recipe this weekend:
but it needs 8 7cm tart rings. I've looked online and the sets available are either too expensive or will not arrive on time. Also why are they all perforated?
Anyway so now I'm thinking of making one big tart and cutting it into pieces as the dessert requires the individual tarts to be broken into three anyway.
What size would you use to convert 8 7cm tartlets to one big tart?
This can be solved using simple math. The area of a circle is calculated as pi * radius2 , so the area of a single tin is about 38.5cm2. 38.5 * 8 is 308, so you need a pan that is 308cm2. Divide that by pi, then get the square root, then multiply by 2 and you get 19.8cm. So you need a 20cm pan, or something close to it.
(This is basically the same answer as GdD's, just with easier math.)
You want to end up with a tart with about the same volume as 8 tartlets, so it'll hold the same amount (= volume*) of filling. Volume is area times depth, but the depth of a tart is the same as the depth of a tartlet, so we've now reduced the problem to one of figuring out the area of 8 tartlets and converting that to one tart.
The formula for area is πr2, but we don't actually have to sit there with a calculator, because the πs cancel each other out:
8 × (7÷2)2 × π = 1 × (x÷2)2 × π ÷2 because 7 cm is the diameter, not the radius
8 × 72 = x2 but it doesn't matter because those cancel out, same as the πs
8 × 49 = x2
We still don't need the calculator, because 49 is basically 50, and 8 times 50 is 400, and the square root of 400 is 20. So you need an approximately 20 cm tart pan to hold the same volume as eight 7 cm tartlet pans.
*straight from the "English has too many words" files
