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| 1. |
If angle between two tangents drawn from an external point is 60 degree then find the length of OP |
| Answer» We know that tangent is always perpendicular to the radius at the point of contact.So, ∠OAP = 90We know that if 2 tangents are drawn from an external point, then they are equally inclined to the line segment joining the centre to that point.So, ∠OPA = 12∠APB = 12{tex}\\times{/tex}60° = 30°According to the angle sum property of triangle-In ∆AOP, ∠AOP + ∠OAP + ∠OPA = 180°{tex}\\Rightarrow{/tex}\xa0∠AOP + 90° + 30° = 180°{tex}\\Rightarrow{/tex}\xa0∠AOP = 60°So, in triangle AOPtan angle AOP = AP/ OA{tex}\\sqrt 3 = \\frac{{AP}}{a}{/tex}therefore, {tex}AP = \\sqrt 3 a{/tex}hence, proved | |