The points (3, 3), (h, 0) and (0, k) are collinear if
1h+1k=13
Let A ≡ (3, 3), B ≡ (h, 0) and C ≡ (0, k). The points A, B, C will be collinear if area of ΔABC = 0
⇒12 [3 (0 – k) + h(k – 3) + 0(3 – 0)] = 0
⇒12 (–3k + hk – 3h) = 0 or 3k + 3h = hk
or 3h+3k=1 or 1h+1k=13