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Daogroupie

Posted: Mon Aug 30, 2010 1:41 pm 

Joined: Wed Mar 04, 2009 2:01 pm Posts: 6550 Location: Herts

Q28: This is a regular hexagon. What is the size of angle x in the shape?
(X is one of the six interior angles) I know that the interior angles are equal in a regular polygon and that the sum of the interior angles in a hexagon is 720 so the answer is 120. But is this a Y6 question? I don't see this anywhere in the KS2 revision guide. My elder dd who is Level 6 maths and did nine entrance exams last year could not do this question and has never seen a question like this before. Has anyone seen a question like this on any other paper? Do I need to start teaching younger dd all about interior and exterior angles in more than just triangles and quadrilaterals at KS2 level?


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beebee

Posted: Mon Aug 30, 2010 3:02 pm 

Joined: Fri Jul 24, 2009 1:10 pm Posts: 32

Hi,
Couldn't the question be looked at as
Looking at the centre of the hexagon, where all the triangles meet is 360 degrees, so one angle is 60 degrees.
As it is a regular hexagon, the triangles have to be regular as well so the other two angles of the triangle have to be equal.
If the first angle is 60 degrees, then the other two angles together must be 120 degrees. So each triangle angle at the edge of the hexagon is 60 degrees.
As the hexagon angle is two of those triangle angles then the angle of the hexagon is 120 degrees.
PS I haven't seen the question, and if I have got the wrong end of it I apologise.


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Daogroupie

Posted: Mon Aug 30, 2010 3:59 pm 

Joined: Wed Mar 04, 2009 2:01 pm Posts: 6550 Location: Herts

This is a very good way of answering the question if you know about the relationship between equilateral triangles and hexagons and the interior angles of a hexagon. Thank you. But is this something a ten year old would have been taught? Is it part of KS2 maths? Thanks


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beebee

Posted: Mon Aug 30, 2010 4:23 pm 

Joined: Fri Jul 24, 2009 1:10 pm Posts: 32

I don't know what 10 year olds should know  I am not a teacher.
I did not comment about whether they were equilateral, I was working on the internal angles of a triangle adding to 180. As the hexagon was regular then the two angles that had to be worked out had to be equal.
I'm not sure what the correct way of doing this question is  this is how I would do it.
PS In fact I didn't know what the internal angles of a hexagon added up to until I read your post


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