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A surprising find

The other day I my timehop showed me this lovely little post from last year. It includes “Heron’s Formula” for calculating the area of a triangle, as I read it I remembered thinking it was a little strange that not many people had heard of it before.

Today I was looking through a number of textbooks trying to find a decent set of questions on area, perimeter and volume for my year nines as I wanted to consolidate their learning at the start then move onto surface area. I’m not a fan of textbook misuse- ie “copy the example and try the questions” but I do sometimes use them for exercises as we have a very limited printing budget and some of them have superb exercises. For a fuller picture on.my view of textbooks, read this.

I was looking in one of my favourite textbooks:

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And I happened across this:

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There it is! Plain as day! Heron’s Formula! In a KS3 textbook!

I was disappointed that its function was described and its name wasn’t and there was no mention of why this worked. It basically reduces the question down from a geometry one to a purely algebraic substitution task and I would question the appropriateness of including it in an exercise on area, but still, I was incredibly exciting to find it there!

Are you a fan of Heron’s Formula? Had you even heard of it? Do you have a favourite textbook? I’d love to hear your views.

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  1. Damian Watson
    April 18, 2015 at 11:36 pm

    This is bringing back memories I used this textbook 7 years ago, and remember this question. St Thomas Mores Blaydon a great set of textbooks, differentiated by letter if I remember correctly. Thanks for the memories. Damian

  2. Mark Heslop
    April 19, 2015 at 11:16 am

    It also appeared on the L5-7 SATS paper in 2005!

    • April 19, 2015 at 11:24 am

      Superb! I’ll have to dig that paper out.

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