Through a fixed point $$P(\alpha, \beta), a$$, variable line is drawn to cut the coordinate axes at $$A$$ and $$B$$. The locus of the mid-point of $$A B$$ is
If a man running around a race-course notes that the sum of the distances of two flag-posts from him is always $$10 \mathrm{~m}$$ and the distance between the flag-posts is $$8 \mathrm{~m}$$, then the area of the path he encloses in square metres is
If a circle of constant radius '$$r$$' passes through the origin and meets the coordinate axes at points $$A$$ and $$B$$ respectively, then the locus of the centroid of triangle $$O A B$$, '$$O$$' being the origin, is
A ray of light is sent along the line $$x-2 y+5=0$$. Upon reaching the line $$3 x-2 y+7=0$$, the ray is reflected from it. The equation of the line containing the reflected ray, is