How to find the surface area of an egg? [duplicate]

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I think this is possible but I don't even know how to go about it.I know everything about ellipse but how can I adjust the shape of an ellipse to the shape of a normal egg

marked as duplicate by Matthew Towers, Start wearing purple, Ayman Hourieh, MathOverview, Lord_FarinJul 8 '13 at 12:01

The way that this is often achieved is by multiplying the usual equation of an ellipse with a shape function $g(x)$ that creates asymmetry with respect to reflection in the $y$-axis, combined with a graduation parameter $t$ $(0\leq t \leq 1)$ so that you get
$$\phi(x) = \sqrt{1 - (x/a)^2} + t~g(x)~(x^2-a^2)$$
with typically $b=1$, $a=1.3$. I have used $g(x) = x^3$ $(x\leq0)$, $g(x) = x^2$ $(x\geq0)$ with $t=0.1$, but the choice is quite broad, as long as it is asymmetric w.r.t. $x$.
I think there are different types of eggs and egg shapes, so there is probably no single $g(x)$ and $t$ that fits all eggs.