As the tangent is a straight line, the equation of the tangent will be of the form \(y = mx + c\). We can use perpendicular gradients to find the value of \(m\), then use the coordinates of P to find ...

In the present investigation, we have identified the stream function solution of the Brinkman equation in both the cardioid coordinates (λ, σ, ζ) and tangent sphere coordinates (τ, η, ζ).