Maths Problem Please Help

OP

Could you elaborate as why you think it is 120 degrees?
I have tried he question a few times but I know the answers I have gotten are wrong.
Any explanation would be appreciated 😄

Reply 6

Original post by Charleslewison

Could you elaborate as why you think it is 120 degrees?
I have tried he question a few times but I know the answers I have gotten are wrong.
Any explanation would be appreciated 😄

its 100 , he's wrong

Reply 7

OP

Original post by Ollie123x

its 100 , he's wrong

Thankyou, please could you explain why it is 100😄

Reply 8

the bear

20

join O to B & look at the triangle OBC.

also look at the triangle OBA

Reply 9

OP

Original post by the bear

join O to B & look at the triangle OBC.

also look at the triangle OBA

So in triangle OBC would angle BOC be 90 degrees because of Theorem 2?

Reply 10

the bear

20

Original post by Charleslewison

So in triangle OBC would angle BOC be 90 degrees because of Theorem 2?

BC is not a diameter and O is not on the edge of the circle, so no.

the triangle is isosceles....

Reply 11

OP

Original post by the bear

BC is not a diameter and O is not on the edge of the circle, so no.

the triangle is isosceles....

Oh I see that now😅 so angle OCB is 40 degrees as is angle OBC and therefore angle BOC would be 100 degrees?

Reply 12

Original post by Charleslewison

Do you just want angle D, on the bottom triangle?

Reply 13

the bear

20

Original post by Charleslewison

Oh I see that now😅 so angle OCB is 40 degrees as is angle OBC and therefore angle BOC would be 100 degrees?

yes !

Reply 14

OP

Original post by Ollie123x

Do you just want angle D, on the bottom triangle?

No I think the question is asking for angle ODA on the top triangle, the smaller one.
(Sorry I have just realised the photograph is upside down😅)

Reply 15

Original post by Charleslewison

Oh I see that now😅 so angle OCB is 40 degrees as is angle OBC and therefore angle BOC would be 100 degrees?

Alternate angle theorem makes COA , 40 degrees that is certain as BC and OA are parallel. I may be mistaken but the bow tie circle theorem allows you to deduce that angle BAO is also 40 which makes the final angle which you want 100...?

Reply 16

Original post by Charleslewison

No I think the question is asking for angle ODA on the top triangle, the smaller one.
(Sorry I have just realised the photograph is upside down😅)

They're the same anyway :smile:

Reply 17

HabibSyed

16

Not only do you give us a difficult math question (For me), but you give it to us upside down? Gheez gheez, settle down Einstein. Is this what makes a grade 9 question?

Reply 18

OP

Original post by Ollie123x

Alternate angle theorem makes COA , 40 degrees that is certain as BC and OA are parallel. I may be mistaken but the bow tie circle theorem allows you to deduce that angle BAO is also 40 which makes the final angle which you want 100...?

Thank you for the help! 😄 Just out of curiosity would angle BDC be 100 as degrees as well?

Reply 19