• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

I need help with an extension 1 circle geometry question. (1 Viewer)

abdullion

New Member
Joined
Mar 18, 2015
Messages
12
Gender
Male
HSC
2016
Please help if you can! The questions is:
AB and AC are two chords of a circle on opposite sides of center O. P and Q are the mid-points of AB and AC respectively. Prove that A, P, O and Q are con-cyclic.
 
Joined
Mar 13, 2015
Messages
100
Gender
Male
HSC
2015
Construct OP and OQ. Since midpoint of AB is P, then the line OP must be perpendicular to the chord (radii bisecting a chord is at a right angle, or a theorem like that). Therefore, angle APO = 90. This is similar with angle AQO. Since Q is midpoint of AC then OQ is perpendicular. Since angle AQO = 90 and angle APO = 90, angle APO + angle AQO = 90+90= 180. Since opposite angles of a quadrilateral are supplementary then the quadrilateral lies on a circle and is therefore concyclic.
 

abdullion

New Member
Joined
Mar 18, 2015
Messages
12
Gender
Male
HSC
2016
I seeeeeee, thank you so much! Haha, seems so simple once you have it explained. Thanks c:
 

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

Top