This is a little murky without the diagram, but I can try to help, assuming that point A is the contact between the wall and the beam and that force P is acting somewhere on the beam, with both x and y components.

- First, recall that the three equations of equilibrium are that the sum of the horizontal forces = 0, the sum of the vertical forces = 0, and the sum of the moments = 0. Therefore...
- R
_{x}will be equal and opposite to the x-component of force P - R
_{y}will be equal and opposite to the x-component of force P - The moment reaction at A will be equal and opposite to the moment
**caused by the vertical component of force P only.** - The horizontal component will not produce a moment, as it acts perpendicularly to the length of the cantilevered beam. This does not cause rotation.
- The vertical component will produce a moment equal to the vertical force times the radial distance from the wall. This is also known as a Torque. Depending on your diagram, the moment will be either clockwise or counter-clockwise
- M
_{A}, the moment reaction, will be equal in magnitude and in the opposite rotational direction to that answer.