Answer: Perpendicular to the line of centres.
- A Parallel to the line of centres
- B Perpendicular to the line of centres
- C The same as the line of centres
- D The common chord extended
Correct answer: B. Perpendicular to the line of centres
Explanation: Radical axis = locus where power w.r.t. both circles is equal. Subtracting circle equations (S₁−S₂=0) gives a linear equation, always perpendicular to the line joining the two centres. For intersecting circles it is the common chord extended. Ans: Perpendicular to the line of centres.
Three standard 3D solids and their key formulas: a cylinder's volume scales with the full height, a cone's volume is exactly one-third of the cylinder with the same base and height, and a sphere's volume and surface area both follow distinct r-based formulas worth memorising separately.
Concept context
Perimeters, areas, and volumes of 2D and 3D shapes