This educational app, Gonio, helps you to understand the core concepts of trigonometric circle, the so-called circle of radius one. Simply by moving your finger, you can use "Gonio" in the study of trigonometric functions such as sine, cosine, tangent and cotangent; furthermore, you can understand how the projections of the sine, cosine, tangent and cotangent work in the unit circle (or trigonometric circle). An easy useful tool both for teachers and for students. Touch and hold top left icon to