\(x\cos\theta + y\sin\theta = 4\) ......(1)
Put \(x = 0\) then \(y\sin\theta =4\)
⇒ \(y = 4cosec\theta\)
Hence, line(1) intersect y-axis at \((0, 4cosec\theta)\)
Put \(y = 0\) then \(x\cos\theta=4\)
\(x = 4\sec\theta\)
Hence, line (1) intersect x-axis at \((4cosec\theta, 0)\)
\(\therefore O(0, 0), A(4\sec\theta , 0), B(0, 4cosec \theta)\).
Centroid of \(\triangle OAB = \left(\frac{0+4\sec\theta +0}3,\frac{0 + 0+4cosec\theta}3\right)\)
\(= \left(\frac 43 \sec\theta, \frac 43 cosec \theta\right)\)