Current Attempt in Progress

A person is sitting with one leg outstretched and stationary, so that it makes an angle of $30\mathrm{.}0$ with the horizontal, as the drawing indicates. The weight of the leg below the knee is $41\mathrm{.}0$ N $,$ with the center of gravity located below the knee joint. The leg is being held in this position because of the force vec$(M)$ applied by the quadriceps muscle, which is attached $0\mathrm{.}100$ m below the knee joint $($see the drawing$).$ Obtain the magnitude of vec$(M).$