Circles (Exercise: 10.6)

Circles


Chapter 10


Exercise 10.6


EX 10.6 QUESTION 1.


Prove that the line of centres of two intersecting circles subtends equal angles at the two points of intersection.

Solution:

Given: Two circles with centres P and Q respectively such that they intersect each other at P and Q.
To Prove: ∠PAQ = ∠PBQ.
Proof: In ∆APQ and ∆BPQ,
PA = PB [Radii of the same circle]
QA = QB [Radii of the same circle]
PQ = PQ [Common]
∴ ∆APQ = ∆BPQ [ SSS congruence criteria]
⇒ ∠PAQ = ∠PBQ [C.P.C.T.]


EX 10.6 QUESTION 2.


Two chords AB and CD of lengths 5 cm and 11 cm respectively of a circle are parallel to each other and are on opposite sides of its centre. If the distance between AB and CD is 6 , find the radius of the circle.

Solution:


EX 10.6 QUESTION 3.


The lengths of two parallel chords of a circle are 6 cm and 8 cm. If the smaller chord is at a distance 4 cm from the centre, what is the distance of the other chord from the centre?

Solution:


EX 10.6 QUESTION 4.


The lengths of two parallel chords of a circle are 6 cm and 8 cm. If the smaller chord is at a distance 4 cm from the centre, what is the distance of the other chord from the centre?

Solution:


EX 10.6 QUESTION 5.


Prove that the circle drawn with any side of a rhombus as diameter, passes through the point of intersection of its diagonals.

Solution:


EX 10.6 QUESTION 6.


ABCD is a parallelogram. The circle through A, B and C intersect CD (produced if necessary) at E. Prove that AE, = AD.

Solution:


EX 10.6 QUESTION7.


AC and BD are chords of a circle which bisect each other. Prove that (i) AC and BD are diameters; (ii) ABCD is a rectangle.

Solution:


EX 10.6 QUESTION 8.


Bisectors of angles A, B and C of a triangle ABC intersect its circumcircle at D, E and F respectively. Prove that the angles of the triangle DEF are 90°–(½)A, 90°–(½)B and 90°–(½)C.

Solution:


EX 10.6 QUESTION 9.


Two congruent circles intersect each other at points A and B. Through A any line segment PAQ is drawn so that P, Q lie on the two circles. Prove that BP = BQ.

Solution:


EX 10.6 QUESTION 10.


In any triangle ABC, if the angle bisector of ∠A and perpendicular bisector of BC intersect, prove that they intersect on the circumcircle of the triangle ABC.

Solution: