Question

A cubical vessel with opaque walls is so placed that the eye of the observer cannot see its bottom but can see the entire wall CD . A small object IS placed at O (O is 10 cm away from corner D)what minimum depth of water should be poured to enable him to see the object clearly?(n=4/3)ANSWER IN CENTIMETE

Answer 1

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Answer 2

i think the answer is 26.7cm.