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9-1 Circle Theorems question HELP!?

Hello, I've worked out the first one as 62 degrees. But which theorem is needed for this? Can someone help? Thanks.

EDIT: Ignore the question b answer, it's wrong, and I have no idea what it is.

HELP.png
(edited 7 years ago)
Original post by Cornelius Scipio
Hello, I've worked out the first one as 62 degrees. But which theorem is needed for this? Can someone help? Thanks.

EDIT: Ignore the question b answer, it's wrong, and I have no idea what it is.

HELP.png


Tangent meets radius at a right angle

For b, AOD is at the centre of the circle, where is ABC ?
Posted from TSR Mobile
(edited 7 years ago)
Original post by gdunne42
Tangent meets radius at a right angle


Posted from TSR Mobile


I know this. How do I work out ABC?
Original post by Cornelius Scipio
Hello, I've worked out the first one as 62 degrees. But which theorem is needed for this? Can someone help? Thanks.

EDIT: Ignore the question b answer, it's wrong, and I have no idea what it is.

HELP.png


i can give you a promt, use the theory that angles in the same segment are equal
Original post by filmaker
i can give you a promt, use the theory that angles in the same segment are equal


Ok, so is angle AOD equal to ABC?
Or is AOD equal to OCB?
I'm confused.
Original post by Cornelius Scipio
I know this. How do I work out ABC?


See edit


Posted from TSR Mobile
Original post by Cornelius Scipio
Hello, I've worked out the first one as 62 degrees. But which theorem is needed for this? Can someone help? Thanks.

EDIT: Ignore the question b answer, it's wrong, and I have no idea what it is.

HELP.png


Where a tangent and a radius meet is 90 degrees.
An angle subtended at the centre from two points is double that at the circumference.

Now go :wink:
Original post by gdunne42
Tangent meets radius at a right angle

For b, AOD is at the centre of the circle, where is ABC ?
Posted from TSR Mobile


In the segment?
Reply 8
Avatar for Amir12
Amir12
1
31?
Original post by Cornelius Scipio
In the segment?


At the circumference........
as suggested above, you could usefully make yourself some notes on circle theorems that you could utilise while doing practice questions and then for last minute revision before exams.


Posted from TSR Mobile
Solution found.
It's 31.
Angle in the center is double than at the circumference.
Thanks guys.
I saw on another website that B=31 degrees but i dont know why
Reply 12
Avatar for ro0002
ro0002
1
So... The angle at the centre is 62° and B is an angle at the circumference so therefore B has to be 31°
The angle at the centre is twice the angle at the circumference
(edited 3 years ago)

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