I have 2 questions regarding mirrors: If you look at yourself in a shiny Christmas tree ball with a diameter of 9.0 cm when your face is 30.0 cm away from it, where is your image? Is it real or virtual? Is it upright or inverted? I know the mirror equation is: (1/object distance) + (1/image distance) = 1/f I know that the object distance is 30.0 cm, but I am confused as to what the 9.0 cm represents. Do I divide that number in half to equal 4.5, and would that number be my radius of curvature? Also I don't understand how you tell if an image is real or virtual, and upright or inverted? Is it just inverted if the number is negative? The other problem is: How far from a concave mirror (radius 27 cm) must an object be placed if its image is to be at infinity? To solve this I set up the mirror equation from above, except I rearranged it to be: (1/f) - (1/image distance) = (1/object distance) so to plug it in it would be: (1/13.5)-(1/infinity)=1/object distance I got the 13.5 by dividing the radius in half. However, I don't get how to solve this problem b/c you can't plug infinity into the calculator. Please help! Thanks!