Prove that the tangent at any point of a circle is perpendicular

Subject

Mathematics

Class

CBSE Class 10

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Sample Papers

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 Multiple Choice QuestionsLong Answer Type

31.

A bucket open at the top, and made up of a metal sheet is in the form ofa frustum of a cone. The depth of the bucket is 24 cm and the diameters of its upper and lower circular ends are 30 cm and 10 cm respectively.Find the cost of metal sheet used in it at the rate of Rs 10 per 100 cm2.
Use π =3.14


32.

In fig., l and m are two parallel tangents to a circle with centre O,touching the circle at A and B respectively. Another tangent at C intersects the line l at D and m at E. Prove that   DOE = 900


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33.

Prove that the tangent at any point of a circle is perpendicular to theradius through the point of contact.


Given: A circle with centre O  and a tangent XYto the circle at a point  PTo prove: OP is perpendicular to XY.Construction:Take a point Q on XY other than P and join OQ.

Proof:  Here the point Q must lie outside the circle asif it lies inside the tangent  XY will become secant to the circle.Therefore,  OQ is longer thanthe radius OPof the circle, That is,  OQ> OP.This happens for every point on the line  XY  expect the point  P.So  OP is the shortest of all the distance of the point O to the points on  XY.And hence  OP is  perpendicular to XY.Hence, proved.


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34.

Two poles of equal heights are standing opposite each other on either sideof the roads, which is 80 m wide. From a point between them on theroad, the angles of elevation of the top of the poles are 60o and 30orespectively. Find the height of the poles and the distances of the pointfrom the poles.


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