Here is a great reference to try and figure out angles. LOOKING FOR BALANCE
If you look at the horses left foot and look at the right foot- you can see it has more heel on the right. The horse doesn't have a lot of toe but its angle is bad. Flares happen when- the hoof is out of balance or its too long. It looks as though because its out of balance its putting more weight on the inside of the foot. It may be the picture but it also looks swollen in its pastern.
Of course the whole horses build/conformation is also a big factor in determining how to trim/shoe properly also.