Hushar Mulga
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In the given figure, O is the centre of the circle. Seg AB, seg AC are tangent segments. Radius of the circle is r and l(AB) = r, Prove that ▢ABOC is a square. 

Chapter 3 – Circle – Text Book Solution

Problem Set 3 | Q 4 | Page 84

In the given figure, O is the centre of the circle. Seg AB, seg AC are tangent segments. Radius of the circle is r and l(AB) = r, Prove that ▢ABOC is a square. 

Proof: Draw segment OB and OC.

l(AB) = r      ……[Given] (I)

AB = AC    ……[`square`] (II)

But OB = OC = r    ……[`square`] (III)

From (i), (ii) and (iii)

AB = `square` = OB = OC = r

∴ Quadrilateral ABOC is `square`

Similarly, ∠OBA = `square`      ……[Tangent Theorem]

If one angle of `square` is right angle, then it is a square.

∴ Quadrilateral ABOC is a square.

In figure 3.84, O is the centre of the circle. Seg AB, seg AC are tangent segments.
solution Proof: Draw segment OB and OC.

l(AB) = r      ......[Given] (I)

AB = AC    ......[`square`] (II)

But OB = OC = r    ......[`square`] (III)

From (i), (ii) and (iii)

AB = `square` = OB = OC = r

∴ Quadrilateral ABOC is `square`

Similarly, ∠OBA = `square`      ......[Tangent Theorem]

If one angle of `square` is right angle, then it is a square.

∴ Quadrilateral ABOC is a square.

Explanation:-

Given that line AB is tangent to the circle with center O and radius r at point B, i.e., AB = r (given condition I). Also, AB = AC (given condition II), and OB = OC = r (given condition III).

From these conditions, we can see that AB = OB = OC = r. Therefore, the points A, B, O, and C form a square (because all sides are equal and opposite sides are parallel).

Now, we know that angle OBA is a right angle because AB is tangent to the circle at point B (Tangent Theorem). Since one angle of the square is a right angle, all angles of the square are right angles. Therefore, the quadrilateral ABOC is a square.

 

Chapter 3 – Circle – Text Book Solution

Problem Set 3 | Q 4 | Page 84

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