A woman pulls a sled which, together with its load, has a mass of m kg. If her arm makes an angle of theta with her body (assumed vertical) and the coefficient of friction (a positive constant) is u , the least force, F, she must exert to move the sled is given by
F=((mg)(u))/((sin theta)+ ( u cos theta))
If u=0.55 , find the maximum and minimum values of F for

Question

A woman pulls a sled which, together with its load, has a mass of m kg. If her arm makes an angle of theta with her body (assumed vertical) and the coefficient of friction (a positive constant) is u , the least force, F, she must exert to move the sled is given by 
F=((mg)(u))/((sin theta)+ ( u cos theta)) 
If u=0.55 , find the maximum and minimum values of F for < theta < pi/2

dumbcow · Answer

max/min values occur when slope of tangent line is zero
take derivative of F and set it equal to 0....solve for theta