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## Homework Statement

You look at yourself in a shiny Christmas tree ball, which has a diameter of 9.63 cm. If your face is 7.81 cm away from the shiny ball, calculate the image distance.

## Homework Equations

???

Thinking I would use

magnification = di/d0

di = 0.0781m

d0 = 0.0963m

## The Attempt at a Solution

-0.811m

This doesn't sound right to me, is this perhaps because di is supposed to be what I'm trying to find out???

If so, would I then assume that the magnification is 0.0781 and I need to times that by 0.0963 to work out di? The the calculations would be as follows;???

m x do = di

di = 0.0781 x 0.0963

= 7.52 x 10^-3 m (3sf)

I think this would be the correct way to work out this question, I just wanted to double check that my second method is correct???