Isosceles and equilateral triangles

Lessons

• 1.
  Find x.
  a)

  
  
  
  
  
  b)

  
  
  
  
  
  c)

  
  
  
  
  
  d)

  
  
  
  
  

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• 2.
  In $\triangle DEF$, $\overline {EY}$ is a perpendicular line to $\overline {DF}$ and $Y$ is the midpoint of $\overline {DF}$. Why is $\triangle DEF$ an isosceles triangle? Show your reasoning.

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