Hello, damanwithdaplan!

If we look at it the right way, we don't need fancy formulas.

Determine: .

Let: . .[1]

The problem becomes: .

From [1], we have: .

And we have this right triangle:Code:* * β| * | * | p * | * α | * - - - - - - - - * 1

Get it?

The two angles are from thesame right triangle!

. . That is,

Therefore: .