2. What is a Tangent Line? The tangent line to a curve at a given point is the straight line that "just touches" the curve at that point
3. Tangent line compared to Secant Line A Tangent line touches the curve at just one point unlike a secant line which touches the graph at two points The slope of a tangent line is a instantaneous slope at one point and a secant lines slope is a approximation or sort of a line of best fit.
4. Why do we need Tangent lines? We use tangent lines to find the slope of a graph at one particular point in order to get that points instantaneous velocity or acceleration.
5. Vertical Tangent Line A vertical tangent line is a line with a infinite or undefined slope, therefore this is an indication of a point that is not differentiable Not Differentiable