Capítulo 4 · Neste capítulo você vai

Triangles

  • know the elements of a triangle and classify it;
  • use the congruence cases LAL, ALA, LLL and LAAₒ;
  • prove the isosceles triangle and the external angle theorem;
  • relate sides and angles and apply triangular inequality.

The name says a lot: tri-angle, three angles. Watch the introductory video lesson and then follow the theory.