While$-$working on a forces problem, you come up with a few different equations for the coefficient of friction between a wooden block and the ground.

Possibility #$1$: $=\frac{m_{1}sincos}{m_2^2}$

Possibility #$2$: $=m_1{m}_{2}sincos$

Possibility #$3$: $=\frac{m_{1}sin}{m_{2}cos}$

The variables stand for the following quantities.

$m_1$ : mass

$m_2$ : mass

$$ : coefficient of friction

$$ : angle

Which equation$($s$)$ can be eliminated on the basis of a units check? Select all that apply.