CBSE 10th Class Mathematics

Past year question paper

Year 2020

SET 1, Code Number – 30/2/1

Question Number – 10

Tangent and circle relation

Pythagoras rule

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# In the given figure, from an external point P, two tangents PQ and PR are drawn to a circle of radius 4 cm with Centre O. If ∠QPR = 90° , then length of PQ is

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This answer was edited.Looking to the figure, we can understand that OQ is perpendicular to QP,

Similarly, OR is perpendicular to PR.

consider the tangents PQ and PR, we get,

PQ = PR……..(tangent from a same point that is P)

AC = BC = 4 cm ………..(radius of the circle)

By considering all the above points, we can prove it that it is a square

So, PQOR is a square.

So since it is a square, so all the sides are same,

OQ = OR = RP = QP

∴ QP = 4 cm