As you practise many problems, you will learn to write the $$\sin$$ and $$\cos$$ terms automatically. One thing to remember is that whenever an inclined plane makes an angle $$\theta$$ with the ground, the component of the weight along the plane is given by $$\sin \theta$$. The component perpendicular to the plane is given by $$\cos \theta$$. You then have to choose the $$+$$ or the $$-$$ sign, according to the coordinate system.
What about $$W_x$$ and $$W_y$$ here?
• $$W_x = W \sin \theta, W_y = W \cos \theta$$
• $$W_x = - W \sin \theta, W_y = W \cos \theta$$
• $$W_x = W \sin \theta, W_y = - W \cos \theta$$
• $$W_x = W \cos \theta, W_y = - W \sin \theta$$