• Got a question on how to use our new website? Check out our user guide here!

Circle geo question (1 Viewer)

Thatstudentm9

Member
Joined
Mar 4, 2017
Messages
44
Gender
Male
HSC
2018
How did I get this wrong I’m year 11 3u finished HSC 2u just for fun I’m doing 3u



Sent from my iPad using Tapatalk
 

fan96

617 pages
Joined
May 25, 2017
Messages
449
Location
NSW
Gender
Male
HSC
2018
The theorem involving angles at the centre and circumference is only true when these angles are subtended by the same arc.

In this case, the angle at the circumference is subtended by the arc .

And the angle subtended by the same arc at the centre is the reflex angle at , which is what you have found instead (obviously, could not be the non-reflex angle).

The non-reflex angle you are looking for is then , and so .

This is easily verified:

is a cyclic quadrilateral.

(opposite angles of a cyclic quad. are supplementary).
 
Last edited:

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top