Code Golf: Build Me an Arc

Answer 1

Ruby, 168 characters

Requires Ruby 1.9 to work

s,e,r=gets.scan(/\d+/).map &:to_i;s/=45;e/=45;G=-r..r;G.map{|y|G.map{|x|a=Math.atan2(-y,x)/Math::PI*4%8;print x|y!=0?a==s||a==e%8?'-/|\\'[a%4]:ae ?' ':8:?o};puts}

Readable version:

start, _end, radius = gets.scan(/\d+/).map &:to_i
start /= 45
_end /= 45

(-radius..radius).each {|y|
    (-radius..radius).each {|x|
        angle = Math.atan2(-y, x)/Math::PI * 4 % 8
        print x|y != 0 ? angle==start || angle==_end%8 ? '-/|\\'[angle%4] : angle_end ? ' ' : 8 : ?o
    }
    puts
}