Isosceles and equilateral triangles

Isosceles and equilateral triangles

Lessons

  • 1.
    Find x.
    a)

    equilateral triangles and angles inside the triangles

    b)

    determining the side length of equilateral triangles

    c)

    Isosceles and equilateral triangles

    d)

    Isosceles triangles


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