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Some(?) of the Parts


Ladder and Cube


At a Glance


Far Horizon

Age 14 to 16
Challenge Level


The radius of the Earth is 6367 kilometres.






After finding the distance along the surface of the Earth from the foot of the lighthouse to the horizon, Clare used Pythagoras' Theorem to find the distance from the top of the lighthouse to the horizon.

What is this distance? Can you explain what you notice?