does anyone know what this is ?

9514 1404 393
Answer:
x = 2
Step-by-step explanation:
The mnemonic SOH CAH TOA reminds you of the relations between trig functions and angle.
Tan = Opposite/Adjacent
tan(θ) = y/x
Sin = Opposite/Hypotenuse
sin(θ) = y/4
The given relation is ...
tan(θ) = 2·sin(θ)
y/x = 2(y/4)
2 = x . . . . . . . multiply by (2x/y)
_____
Additional comment
Then the angle can be found from the relation ...
Cos = Adjacent/Hypotenuse
cos(θ) = x/4 = 2/4 = 1/2
θ = arccos(1/2) = 60°
and the value of y is ...
y = 4·sin(60°) = 2√3