Windstream
Ojk's Precalculus Study Page: Sum and Difference Formulas for Tangent
This tutorial introduces the sum and differnce formulas for tangent, and gives several examples of problems to be solved as well as proving other identities. Assumes knowledge of the sum and difference formulas for sine and cosine.
Illustrative Mathematics
Illustrative Mathematics: G Gpe, N Rn, F Tf Coordinates of Equilateral Triangles
In this task, students are asked if there is an equilateral triangle ABC where two vertices are on the x-axis, and all vertices have integer coordinates. Aligns with G-GPE.B, N-RN.B, and F-TF.C.9.