Mathswatch proof of circle theorems

Watch
Afif8011
Badges: 8
Rep:
?
#1
Report Thread starter 1 year ago
#1
question 4
please anyone know how to do this??
Attached files
0
reply
ghostwalker
  • Study Helper
Badges: 17
#2
Report 1 year ago
#2
(Original post by Afif8011)
question 4
please anyone know how to do this??
Consider the angle OBQ - what is is?

Hence what's OBC?

And carry on.
1
reply
Afif8011
Badges: 8
Rep:
?
#3
Report Thread starter 1 year ago
#3
Sorry this time calculated both but no marks were given, do you have any full answer, would really appreciate that.
(Original post by ghostwalker)
Consider the angle OBQ - what is is?

Hence what's OBC?

And carry on.
0
reply
ghostwalker
  • Study Helper
Badges: 17
#4
Report 1 year ago
#4
(Original post by Afif8011)
Sorry this time calculated both but no marks were given, do you have any full answer, would really appreciate that.
No, I don't have a full answer; and it's against forum rules.

You can post working if you'd like it checked
1
reply
Afif8011
Badges: 8
Rep:
?
#5
Report Thread starter 1 year ago
#5
(Original post by ghostwalker)
No, I don't have a full answer; and it's against forum rules.

You can post working if you'd like it checked
Yes please, how do I improve this?
Attached files
0
reply
ghostwalker
  • Study Helper
Badges: 17
#6
Report 1 year ago
#6
(Original post by Afif8011)
Yes please, how do I improve this?
Well OBC doesn't equal x. You're perhaps being mislead by the inclination of OC; remember the diagram isn't drawn accurately. See my first post on determining CBO.
0
reply
Afif8011
Badges: 8
Rep:
?
#7
Report Thread starter 1 year ago
#7
(Original post by ghostwalker)
Well OBC doesn't equal x. You're perhaps being mislead by the inclination of OC; remember the diagram isn't drawn accurately. See my first post on determining CBO.
Ahh well I'm struggling to get my head around this, I don't know what OBC or the rest are equal to
0
reply
ghostwalker
  • Study Helper
Badges: 17
#8
Report 1 year ago
#8
(Original post by Afif8011)
Ahh well I'm struggling to get my head around this, I don't know what OBC or the rest are equal to
OBQ = 90 = OBC + CBQ

And you know what CBQ is from the diagram. Hence....
0
reply
Afif8011
Badges: 8
Rep:
?
#9
Report Thread starter 1 year ago
#9
(Original post by ghostwalker)
OBQ = 90 = OBC + CBQ

And you know what CBQ is from the diagram. Hence....
tried, doesn't work bro
Attached files
0
reply
ghostwalker
  • Study Helper
Badges: 17
#10
Report 1 year ago
#10
(Original post by Afif8011)
tried, doesn't work bro
Sorry, should have said CBO instead of OBC, although it's the same angle.

The question asks you to work out 4 angles in terms of x, before showing that y=2x

You have DCO correctly.

Then.

OBQ = 90 = CBO + CBQ

So, what's CBO in terms of x (it will also include some number(s)), given that CBQ is 2x?
0
reply
Afif8011
Badges: 8
Rep:
?
#11
Report Thread starter 1 year ago
#11
(Original post by ghostwalker)
Sorry, should have said CBO instead of OBC, although it's the same angle.

The question asks you to work out 4 angles in terms of x, before showing that y=2x

You have DCO correctly.

Then.

OBQ = 90 = CBO + CBQ

So, what's CBO in terms of x (it will also include some number(s)), given that CBQ is 2x?
Still doesn't work :/, but thanks for trying
Attached files
0
reply
ghostwalker
  • Study Helper
Badges: 17
#12
Report 1 year ago
#12
(Original post by Afif8011)
Still doesn't work :/, but thanks for trying
Why do you think CBO is equal to x?
0
reply
Afif8011
Badges: 8
Rep:
?
#13
Report Thread starter 1 year ago
#13
I'm just dumb lol, idk what it is
(Original post by ghostwalker)
Why do you think CBO is equal to x?
0
reply
GiveMeCoffee4
Badges: 9
Rep:
?
#14
Report 1 year ago
#14
It's not quite CBO that's x, look at the radii and think about isoceles triangles. Which one is the same base as angle x?
0
reply
Afif8011
Badges: 8
Rep:
?
#15
Report Thread starter 1 year ago
#15
I think DCO and OCB equals to x as isosceles triangle has two equal angles
(Original post by GiveMeCoffee4)
It's not quite CBO that's x, look at the radii and think about isoceles triangles. Which one is the same base as angle x?
0
reply
GiveMeCoffee4
Badges: 9
Rep:
?
#16
Report 1 year ago
#16
DCO is definitely x. Before you find OCB, you need to find OBC. Think about angles from radii to tangents
(Original post by Afif8011)
I think DCO and OCB equals to x as isosceles triangle has two equal angles
0
reply
ghostwalker
  • Study Helper
Badges: 17
#17
Report 1 year ago
#17
(Original post by Afif8011)
I think DCO and OCB equals to x as isosceles triangle has two equal angles
The two isosceles triangles are not congurent. They have different angles.

Your reasoning for angle DCO is correct. You're given the angle ODC and this equals the angle DCO.

You can't use any of that information for the triangle OCB, as it's a completely different triangle with different angles.

What you do know is OBQ is a right angle, i.e. equals 90 degrees, and CBQ = 2x.

Hence looking at the diagram angle OBC = 90 - angle CBQ = ...
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Should there be a new university admissions system that ditches predicted grades?

No, I think predicted grades should still be used to make offers (624)
33.75%
Yes, I like the idea of applying to uni after I received my grades (PQA) (778)
42.08%
Yes, I like the idea of receiving offers only after I receive my grades (PQO) (364)
19.69%
I think there is a better option than the ones suggested (let us know in the thread!) (83)
4.49%

Watched Threads

View All
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise