2016 · Q72
Consider a circle with centre at C. Let OP, OQ denote respectively the tangents to the circle drawn from a point O outside the circle. Let R be a point on OP and S be a point on OQ such that OR x SQ = OS x RP. Which of the following statements is/are correct?
- 1If X is the circle with centre at O and radius OR, and Y is the circle with centre at O and radius OS, then X = Y.
- 2∠POC+ ∠QCO = 90°
Select the correct answer using the code given below.
Elementary MathematicsCircles
- A1 only
- B2 only
- CBoth 1 and 2
- DNeither 1 nor 2
Explanation
Put OP = OQ = L, OR = r₁, OS = r₂: OR·SQ = OS·RP becomes r₁(L−r₂) = r₂(L−r₁), so r₁ = r₂ and the two O-centred circles coincide — statement 1 true. With C = (0,0), O = (d,0): ∠POC = arcsin(r/d) and ∠QCO = arccos(r/d), summing to 90° — statement 2 true. Hence both, option C.