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    Help With A Geometry Question Please!! (Triangles) Ingo

    In my Project Maths book (Text and Tests 2 Junior Cert Higher Level Maths) there is a question (pg 174 question 6 (c)) that shows a triangle and tells you to explain why the angle ABC is 90 degrees by marking equal angles. Could someone please explain how to do it? (I have attached a picture of the question) Thank you!

    attachment Maths Question.docx

    1. avatar image

      Hiphop

      Hi, so you just need to work with the bigger triangle! (triangleABC)

      First label the angles:

      ∠CAB = ∠1

      ∠ABX = ∠2

      ∠XBC = ∠3

      ∠ACB = ∠4

      We know:

      ∠1 + ∠2 + ∠3 + ∠4 = 180°

      ∠1 = ∠2

      ∠3 = ∠4

      Therefore,

      ∠2 + ∠2 + ∠4 + ∠4 = 180°

      ∠2 + ∠4 = 90°

      :)

    2. avatar image

      Ingo

      Thanks so much!! I think I was confusing myself by overthinking. Thank you! :)

    3. avatar image

      Hiphop

      No problem!! :)

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      Me

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