My Math Forum Area of irregular Polygon

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 August 23rd, 2017, 06:42 AM #1 Senior Member   Joined: Jan 2015 From: London Posts: 108 Thanks: 2 Area of irregular Polygon Hi here is the image of a polygon that I need to find the area of, my dad set me this challenge and I am not back at school yet, for anyone thinking this is homework. Also, there are right angles at the top right and bottom right I was thinking splitting it up into smaller triangles but after the first one didn't really know where to go from there. Last edited by jamesbrown; August 23rd, 2017 at 06:46 AM.
 August 23rd, 2017, 07:22 AM #2 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 12,750 Thanks: 860 Change the lengths (clockwise from top) to: 39,53,37,36,24,12 (easier to work with; change them back later). Flip diagram sideways so that "53" is on y-axis and "37" is on x-axis: so diagram fully in 1st quadrant. Go to town with that: that's all you get from me, since you did not label your diagram!! Last edited by greg1313; August 23rd, 2017 at 07:25 AM.
August 23rd, 2017, 07:46 AM   #3
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Quote:
 Originally Posted by Denis Change the lengths (clockwise from top) to: 39,53,37,36,24,12 (easier to work with; change them back later). Flip diagram sideways so that "53" is on y-axis and "37" is on x-axis: so diagram fully in 1st quadrant. Go to town with that: that's all you get from me, since you did not label your diagram!!
First off I thought of this method myself and was confused with how you would find the gradient of the lines at the side? And thanks for the advice also I don't understand what you meant by not labelling my diagram - as all I missed out was the 2 right angles which I then added in at the bottom - that was all I was given by my dad so there isn't much else I could have labelled sorrry

 August 23rd, 2017, 07:57 AM #4 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 12,750 Thanks: 860 I meant labelling the vertices; like AB being the top line (3.86); then going clockwise, ending up with polygon ABCDEF.
August 23rd, 2017, 08:05 AM   #5
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Quote:
 Originally Posted by Denis I meant labelling the vertices; like AB being the top line (3.86); then going clockwise, ending up with polygon ABCDEF.

Edit:
still don't understand like if I'm plotting the points, I need 2 values to plot. Like I get the top line cause it's straight but when trying to do BC I wouldn't know where to plot it because I don't know the height nor the length? I only know the hypotenuse if you understand?

Last edited by jamesbrown; August 23rd, 2017 at 08:11 AM.

 August 23rd, 2017, 12:15 PM #6 Senior Member   Joined: Jan 2015 From: London Posts: 108 Thanks: 2 All good my dad added an extra measurement in and was able to calculate it!

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