HELP

[lyric delta]

please help

[wispy canopy]

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[gilded turret]

Try using the intersecting secants theorem.

[lyric delta]

I think maybe it's wrong because how can a chord AB be bigger than the diameter CD

[gilded turret]

Let's see. Your solution seems correct, so let me just check.
PB*PA = PD*PC
We have PB = PA - AB, PC = PD + CD. So:
PA(PA - AB) = PD(PD + CD)
So, from here:
AB = PA - PD(PD + CD)/PA = 8 cm - 4 cm(4 cm + 3 cm)/(8 cm) = 4.5 cm
Well, they have PA > PC, which can't happen anyway. I think they just picked numbers without thinking too much. Your answer is correct, though.

[lyric delta]

I just saw that they've not specified wheter DC is diameter or not, thank you for your help!

[compact garden]

@lyric delta has given 1 rep to @gilded turret