Tangent Line Approximation
Enter a function into the input box for f(x). The value of a is the x-coordinate for the point of tangency for the tangent line.  Input values for a into the input box, or drag the slider to see the tangent line move.  Input an x-value to see the tangent line approximation using this x-value.  Click the "Show Coordinates" box to see the point coordinates to use for a tangent line approximation.