A sector `O A B O` of central angle `theta` is constructed in a circle with centre `O` and of radius `6.` The radius of the circle that is circumscribed about the triangle `O A B ,` is `6costheta/2` (b) `6sectheta/2` `3sectheta/2` (d) `3(costheta/2+2)`

Explanation

`R=(abc)/(4D)`

`D=1/2*6*6sintheta`

`D=18sintheta`

`a=6,b=6`

`sin(theta/2)=C/12`

`C=12sin(theta/2)`

`R=(6*6*12sin(theta/2))/(4*18sintheta)`

`R=(6sin(theta/2))/sintheta`

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