The unit circle, when understood, helps student understand how sine, cosine and tangent of angles is calculated for angles greater than 90 degrees. It helps them understand the signs of the values, and helps them remember basic output values. It is a great way to establish a solid conceptual foundation in trigonometry for students. (Note: Students need command of the two special right triangles, the isosceles and 30 – 60 – 90 triangles. )What you’ll get with this lesson is a zip file containing