The straight line through two points will have an equation in the form \(y = mx + c\). Then, we can find the value of \(c\), the \(y\)-intercept, by substituting the coordinates of one point into the ...

As a tangent is a straight line it is described by an equation in the form \(y - b = m(x - a)\). You need both a point and the gradient to find its equation. You are usually given the point - it's ...