In an isosceles ΔABC, the base AB has produced both ways in P and Q such that AP×BQ=AC2.
Prove that ΔACP∼ΔBCQ.
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Given, an isosceles triangle ABC having base AB and AC = BC.
Also, AP×BQ=AC2⇒APAC=ACBQ⇒APAC=BCBQ
To prove that ΔACP∼ΔBCQ.
Proof :
Given, AC = BC ........ (2)
⇒ ∠CAB = ∠CBA [Angles opposite to equal sides are equal]
Again, ∠CAB + ∠CAP = 180° and ∠CBA + ∠CBQ = 180° [Both forming a linear pair]
⇒ ∠CAB = 180° – ∠CAP and ∠CBA = 180° – ∠CBQ
⇒ 180° – ∠CAP = 180° – ∠CBQ [using (2)]
⇒ ∠CAP = ∠CBQ
Now, In ΔAPC and ΔCBQ, we have
∠CAP = ∠CBQ
APAC=BCBQ
⇒ΔACP∼ΔBCQ.(SAS similarity)
Hence Proved