Question No. 12
If BC and OB are
equal to 8 cm and
5 cm
5
respectively.
then find the value of
3AO in cms
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Answered by
2
Answer:
i think 25 is the correct answer...
Answered by
1
Step-by-step explanation:
OB=OC=5cm (Radius of circle)
BC is chord of circle
BC=8cm
BM=MC=4cm ( Perpendicular bisector from centre of circle bisects the chord)
Area of Triangle AOB=1/2*AB*OB
Area of Triangle AOB=1/2*OA*BM
1/2*AB*OB=1/2*OA*BM
AB*5=OA*4
AB/OA=4/5
In Right angled triangle AOB
By using pythagoras theorem
AB^2+OB^2=OA^2
(4/5*OA)^2+25=(OA)^2
16/25*OA^2+25=OA^2
25=OA^2-(16/25)*OA^2
25=9/25*OA^2
Taking square root on both sides
5=3/5*OA
5*5/3=OA
25/3=OA
25=3*OA
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