Q- ᴡʀɪᴛᴇ ᴛʜᴇ ᴘʀᴏᴏꜰ ɢɪᴠᴇɴ ᴡɪᴛʜ ᴛʜᴇ ᴛʜᴇᴏʀᴇᴍ ᴏꜰ ᴄʏᴄʟɪᴄ Qᴜᴀᴅʀɪʟᴀᴛᴇʀᴀʟ
ᴛʜᴇᴏʀᴇᴍ: ᴏᴘᴘᴏꜱɪᴛᴇ ᴀɴɢᴇʟꜱ ᴏꜰ ᴀ ᴄʏᴄʟɪᴄ Qᴜᴀᴅʀɪʟᴀᴛᴇʀᴀʟ ᴀʀᴇ ꜱᴜᴘᴘʟᴇᴍᴇɴᴛᴀʀʏ
Class : 10th
Answers
Answer:
Theorem: Prove the opposite angles of a Cyclic Quadrilateral is Supplementary i.e have the sum of 180°.
Given: Cyclic Quadrilateral PQRS for a Circle with centre O.
To Prove: <P + <Q =180°
<Q + <S =180°
Construction: Join OS and OQ.
Proof: Arc QPS subtends <SOQ at the centre and <SRQ at the remaining part of the circle.
Therefore, <SOQ = 2<SRQ.
Major arc SRQ subtends reflex angle SOQ at the centre and <SOQ on the remaining part of the circle.
Therefore, Reflex <SOQ= 2<SPR
2x + 2y = 360°.
Therefore, x+y = 180°.
Hence, <P + <R = 180°.
Now in Quadrilateral PQRS,
<P + <Q + <R + <S = 360° [Angle Sum Property]
(<P + <R) + <Q + <S = 360°
i.e. 180° + <Q + <S = 360°
Therefore, <Q + <S = 360° - 180°
= 180°
Hence, <Q + <S = 180°.
[Sorry if the figure's a bit messy.. I drew it in a hurry.]
P. S. If you have any doubt s regarding this, you can ask me down in the comments. I will be Happy to Help :D
I Purple You!