6. A rod of length 12 cm moves with its ends always touching the coordinate axes. Determine the equation of the locus of a point P on the rod, which is 3 cm from the end in contact with the x-axis.
Let be the angle that rod makes with the ground,
Now, at a point 3 cm from the end,
At the point touching the ground
Now, As we know the trigonometric identity,
Hence the equation is,