# Derivative at several points for sine function

- Author:
- alfinio

- Topic:
- Derivative, Sine

Tools for finding tangent lines to sine function for known angles

Use the horizontal segment to find the

*x*values where the slope of the tangent line is zero. Use the segment at 45˚ to find the*x*values where the slope of the tangent line is 1. Use the segment at 135˚ to find the*x*values where the slope of the tangent line is -1. Use the side of the triangle at 30˚ to find the*x*values where the slope of the tangent line is √3/3 = 0.577... Use the side of the triangle at 150˚ to find the*x*values where the slope of the tangent line is - √3/3 = - 0.577..