Answer: Both A and B.
- A 2g₁g₂ + 2f₁f₂ = c₁ + c₂
- B The angle = 90°
- C Both A and B
- D Neither A nor B
Correct answer: C. Both A and B
Explanation: Orthogonal intersection means tangents at the meeting point are perpendicular (angle=90°). Using r₁²+r₂²=d² (sum of squared radii = squared distance between centres), this reduces to 2g₁g₂+2f₁f₂=c₁+c₂. Both statements are equivalent. Ans: Both A and B.
The slope of a line is the ratio of vertical change (rise) to horizontal change (run) between any two points on it - equivalently, the tangent of the angle θ the line makes with the positive x-axis.