Projection of the tangent of a point on the curve: ().

Or analysis: let the tangent point be, because, so, so the tangent equation is, because it crosses the point, so. So the tangent equation is or. Test site: the geometric meaning of derivative. Comments: The derivative of the curve at a certain point is the slope of the tangent of the curve at that point. We should skillfully apply the geometric meaning of derivative to find the tangent equation of curve, and pay attention to the difference between the tangent equation at a certain point and the tangent equation passing through a certain point.