1. The problem statement, all variables and given/known data A person pulls on a block with a force F, at an angle theta with respect to the horizontal. The coefficient of friction between the block and the ground is mu. For what theta is the F required to make the block slip a minimum. 2. Relevant equations Net force equations for static objects 3. The attempt at a solution So I'm pretty sure I've got all of my equations right, but I'm having trouble simplifying my results further. [tex]Ff=\mu N[/tex] when the box slips and [tex]N=Mg-Fsin\theta[/tex] Substitution gives [tex]\mu\left(Mg-Fsin\theta\right)=Fcos\theta[/tex] I don't know how to solve for theta.