Class Agenda #6: Brainiacs

Student Learning Target: 

  • I can use similarity to define trigonometric ratios as properties of the angles in a right triangle.

Opening problem:

  • List all of the properties you know about similar triangles.
  • How certain are you that your theoretical values are accurate? Why?

Here is your chart from Thursday:

Brainiacs Measurements

In conclusion:

  • The trigonometric ratios are SINE, COSINE, and TANGENT

  • These ratios are properties of the angles in similar triangles.

  • So, are rectangles and squares similar?

We can now define similarity, with all of it’s properties!

But wait, what are the trig ratios (and how can I remember them)?

  • Let’s build some reminders for ourselves!

Next Step: A Fascinating Chart


  • Problem Set #3
  • Final part of project (Now due Thursday, February 14th)
  • Delta Math

Example Problem:

Jasmine has two triangles with equal angle measurements:

Screen Shot 2013-02-10 at 2.36.08 PM

The sides of one triangle are 4, 6, and 8. The sides of the other triangle are 9, 6, and 12. She says that the triangles are not similar because:

4/9 = 0.444, 6/6= 1, and 8/12 = 0.667

Do you agree with Jasmine? Thoroughly explain your answer.

Work time!


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