Formula 1 rebus

Question

We're not talking about the motorsport, but about one of the most famous formulae in mathematics. It's also slightly rearranged and in a form of the rebus:

Hint

The answer is a single letter.

Answer 1

The answer is

$\pi$

As observed by Beastly Gerbil, the first half of the rebus is

$\frac1i$

because

January is the first month and an eye is the universal rebus of 'i'.

The image of the log represents

logarithm

The thermometer and the coal represent

$-1$

because

30.2° F is -1° C. The coal appearing beneath the line represents removing the 'C' because coal is carbon, whose elemental symbol is 'C'.

So the second part becomes

$\log(-1)$

We know that

$\log(-1) = i\pi$ from Euler's Equation, $e^{iπ} + 1 = 0$,

so the second part is

$i\pi$

Given the first part we end up with:

$\frac{i\pi}i$

which is just

$\pi$

Answer 2

Currently unsure about the last part but the first part is

$\frac1i \log \left(\frac{30.2?}{?}\right)$

because

January is the first month and its over an eye and then there is a log and it then might be 30.2 because that is the number shown

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EDIT:

Well done @Silenus, who worked out that

The last part is -1 because 30.2 F is -1 C (Coal indicates C). This means that the equation is:

$\frac1i \log (-1)$

Which is

$\frac{i\pi}i$

Which is simply

$\pi$