Splitting forces into components

[prune1]

Homework Statement

This problem is actually a worked out solution BUT i don't see where certain things come from...namely how the forces are split into their components. If you look at the attachment, you can see the weight is split into components mgsin and mgcos...I just do not see how this is worked out. I think the axis is being chosen so that the above mgsin and mgCos are parallel and perpendicular to the slope but how do you know which is which? I can't see how this works at all...Please please someone explain to me what weird rotation has gone on here so that the sins and cos are obtained?...

I mean, for example, Fg is acting straight down right, and IT would be the opposite side from where the angle is, so using trigonometry, the component of Fg acting parallel to the slope should be mg/Sin and not mgSin surely?! So confused...

I don't normally have difficulty splitting forces, this one is just odd for some reason and it's put me off completely.

Thanks in advance to ANY who can help!

 

[member 553083]

Homework Equations F = maThe Attempt at a SolutionThe weight of the block is mg, where m is the mass of the block and g is the acceleration of gravity. The force of gravity can be split into two components: mgsinθ and mgcosθ. The mgsinθ component is parallel to the slope and the mgcosθ component is perpendicular to the slope.