Mathematics

In the given figure, in △ABC, ∠B = 90°. If ABPQ and ACRS are squares, prove that:

(i) △ACQ ≅ △ABS

(ii) CQ = BS.

In the given figure, in △ABC, ∠B = 90°. If ABPQ and ACRS are squares, prove that: R.S. Aggarwal Mathematics Solutions ICSE Class 9.

Triangles

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Answer

(i) From figure,

In △ACQ,

⇒ ∠BAC = ∠QAC - ∠QAB

⇒ ∠QAC = ∠BAC + ∠QAB

⇒ ∠QAC = ∠BAC + 90° ….(1)

In △ABS,

⇒ ∠BAC = ∠BAS - ∠CAS

⇒ ∠BAS = ∠BAC + ∠CAS

⇒ ∠BAS = ∠BAC + 90° ….(2)

From eq.(1) and (2), we have:

⇒ ∠QAC = ∠BAS

In △ACQ and △ABS,

⇒ ∠QAC = ∠BAS [Proved above]

⇒ AQ = AB [Sides of square ABPQ]

⇒ AC = AS [Sides of square ACRS]

∴ △ACQ ≅ △ABS (By S.A.S axiom)

Hence, proved that △ACQ ≅ △ABS.

(ii) As,

△ACQ ≅ △ABS

∴ CQ = BS [Corresponding parts of congruent triangles are equal]

Hence, proved that CQ = BS.

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