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Shilpa Das from KENDRIYA VIDYALAYA KANJIKODE, asked a question
Subject: Math , asked on 20/2/12

to draw a pair of tangents to a circle which are inclined to each other at an angle of 100o it is required to draw tangents at end points of those two radii of the circle, the angle between which should be??

EXPERT ANSWER

Lalit Mehra , Meritnation Expert added an answer, on 21/2/12

PA and PB are tangents drawn from an external point P to the circle.

∠OAP = ∠OBP = 90°         (Radius is perpendicular to the tangent at point of contact)

In quadrilateral OAPB,

∠APB + ∠OAD + ∠AOD + ∠OBP = 360°

∴ 100° + 90° + ∠AOB + 90° = 360°

⇒ 280° + ∠AOB = 360°

⇒ ∠AOB = 360° – 280° = 80°

Thus, the angle between the two radius, OA and OB is 80°.

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Prachi Patel From J.h Ambani Saraswati Vidya Mandir, added an answer, on 20/2/12
30 helpful votes in Math

the angle between the two radius will be 80 degree . its is so because the tangents meet at 90 degree and the angles are inclined at 100 degree so adding 100 degree + 90 degree + 90 degree + the angle between the radii ( say x) = 360 degree  so the value of x is 80 degree.

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Shilpa Das From Kendriya Vidyalaya Kanjikode, added an answer, on 20/2/12
183 helpful votes in Math

 can u xplain me with a figure..

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Shilpa Das From Kendriya Vidyalaya Kanjikode, added an answer, on 20/2/12
183 helpful votes in Math

hw u got 80o??

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