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# T4 maths exterior sides watch

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1. Can anyone explain this question. Answer is 15. Not sure what the question is asking.
2. When you walk all the way round the exterior of a polygon, pointing your arm out in front of you, you will see that your arm turns through 360 degrees. It only turns through an angle when you get to a vertex, a point where two sides meet.

If the polygon has 8 equal external sides, then it also has 8 equal external angles (i.e. the angles made between each of the external sides). So if the size of the external angle is , then we must have from which we can find .

In your case, you can find the external angle for the shape by geometry, but you need to find the number of sides , say. Can you finish this? You need to write down an equation similar to the one I gave above, then solve it.
3. you need to find the acute angles in the trapezia. then find the internal angle of the big polygon.... then the external angle.... then the number of sides.
4. So the tiles continue to form a full circle? I understand now I think.

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Updated: January 22, 2017
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