Is there any other method to draw the cross section but without using FF'E'E plane?

Question

Given that a regular pyramid T.ABCD in which

• P is on TC such that TP:PC = 1:3
• R is on the extension of BC such that BR:BC = 1:3
• Q is arbitrarily on the plane TAD but neither outside nor on the boundary

Draw the cross section when the plane PQR cuts the pyramid.

My own solution is as follows.

Question

Is there any other method to draw the cross section but without using FF'E'E plane?

Answer 1

Hint.

We have that given $P, Q$ and $R$ follows $\vec n = (Q-P)\times(R-P)$and the sought plane is given by

$$ \Pi \to (p-Q)\cdot\vec n = 0 $$

with $p = (x,y,z)$