Saturday, 2 October 2010

Year 8 maths Homework and the internal angles of a polygon.....done.

The night before last I helped my son with his maths homework. He is in year 8 and it consisted of working out the angles of some shapes, mostly triangles within polygons.I enjoyed it - its like a puzzle and when you get the first couple the others come like a waterfall of knowledge.

However, the next part was not quite as easy. You had to work out the internal angles of a nonagon - a nine sided shape. Well, I just did not know how to do it and it frustrated me. In the end we had to give up. The next day I was on a mission to work them out. Am I slightly obsessive....?

I asked people in my staff room, but nobody seemed to know. Then I googled nonagon and found the most interesting site. It gave me a formula which I could use to work out the internal angles of any polygon. Why I would want or need to do that is a mystery, but if I am ever called upon in the course of my everyday life to work out the internal angles of any multi sided shape, be it regular or irregular, I am now equipped with the knowledge to do so.

You need the equation:   180(n-2)      

This means that, taking n as the number of internal angles, you take 2 away from it then multiply by 180.

So.... a nonagon.... a nine sided shape is 9-2 then x180....  so 7 x 180 which = 1260.

My thirst for knowledge is satisfied. All I need now is somebody to desperately need to know the total of the internal angles of ...... something.

This was brought to you by Secret Housewife Homework Solutions.


Gail said...

That must be very entertaining...I have trouble seeing the angles in my life, without looking at the math problem. Proud of you!

Caz said...

Ahhh, that's a polygon!!!!!

The Age of Aquarius said...

Just what I was googling for....LOL...what a life saver