EASY TRIGONOMETRY

By the pythagorean theorem, $QR=\sqrt{13^2-12^2}=\sqrt{169-144}=\sqrt{25}=5$ .

$\tan~P - \cot~R=\dfrac{5}{12}-\dfrac{5}{12}=$ $\color{#D61F06}\large \boxed{0}$

TAN P = QR/PQ COT R = QR/PQ HENCE TAN P - COT R = QR/PQ - QR/PQ = 0

x/12 -x/12=0