6 resources.
How the derivative gives the tangent's slope and the normal's slope is its negative reciprocal, with a worked example.
Finding the slope of a tangent line to a curve at a given point, with worked examples on a cubic and a rational function.
The section formula for a point dividing a segment internally or externally, and finding a midpoint, with worked examples.
The differences between a line segment, a ray, and a line, and what makes points or lines collinear or concurrent.
The determinant formula for the area of a triangle from its vertex coordinates, with a worked example.
Using the cross product to find the area of a triangle or parallelogram from vertex or side vectors, with worked examples.