FORMULABANK

The "Apple" Formula
The name comes from the sound of reading the formula, which sounds like "half a b sine."
You need to know two sides and the angle between those two sides.

Area = 1/2 a·b·sin(C)
You can choose any angle as C, but remember that the sides you use must be the legs of the angle you know.

$\frac{1}{2}\cdot 3,16\cdot 4\cdot \sin (108,43)\approx 5,995851$