Performed by students of the triangle (triangle) and the triangle for determining when a triangle enclosed in a circle. Triangle will be able to apply a formula for calculating the area of a triangle is shorter and faster with more accuracy possible. The study circle (circle) and trigonometric functions, the sine, cosine and tangent to the relationship between a triangle and a circle
, and the final step is to check the authenticity of the area of a triangle is given by the. of a triangle and a circle using the Geometer's Sketchpad operating results found.