A robot, which is initially facing North, is programmed to travel 5m then turn through 10∘ , travel 5m then turn through 20∘ , travel 5m then turn through 30∘ , and so on. Each move consists of moving 5m in a straight line and then turning clockwise through an angle which increases by 10∘ at each move.

How far has it travelled by the time it is first facing due East at the end of a move?