Teorema de Carnot. Lema 1

Topic:Addition, Algebra, Angles, Area, Calculus, Circle, Circumcircle or Circumscribed Circle, Constructions, Cosine, Geometry, Incircle or Inscribed Circle, Limits, Line Segment, Straight Lines, Median Value, Multiplication, Numbers, Orthocenter, Pie Chart or Circle Chart, Plane Figures or Shapes, Planes, Quadrilaterals, Rectangle, Reflection, Secant Line or Secant, Sine, Subtraction, Tangent Line or Tangent, Triangles, Trigonometry, Unit Circle