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If `A , B , C` are three points on a circle with centre `O` such that `/_A O B=90^@` and `/_B O C=120^@,` then `/_A B C=` `60^@` (b) `75^@` (c) `90^@` (d) `135^@`

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`A, B and C` are three points on a circle with centre`O`
`/_AOB=90^@ \and\ /_BOC=120^@`
`/_AOC=360^@−(120^@+90^@)=360^@−210^@=150^@`
But `/_AOC`is at the centre made by are `AC \and\ /_ABC`at the remaining part of the circle
`/_ABC=1/2/_AOC=1/2xx150^@=75^@`
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RD SHARMA-CIRCLE -All Questions
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