Condition for Perpendicularity of Two Straight Lines
AB is a chord...
Question
AB is a chord of length 16cm of circle of radius 10cm the tangents at A and B intersect at point P. Find the length of PA.
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Solution
AT = TB (perpendicular from centre bisect the chord) ΔAOT,OT=√102−82=6 ΔPAO,∠OAP=90∘ ∠AOP=tanθ=PAOA ....(i) ΔAOT,∠AOT=tanθ=ATOT=86 ..(ii) So, from (i) and (ii) 86=PA10∴PA=403cm