Can i connect two old Sharp speakers to Yamaha receiver?
Yes, you can connect them, but you really should get something much better. I would call them "VERY short term stand-ins" for another pair of CS-260s.
I wouldn't. Those are really crappy speakers, and you could easily get much better ones for relatively little money, and ones that far better matched your front speakers. Plus, I would not use any speakers that came off of a cheap and old all-in-one system, and definitely not speakers with wires that go into them and cannot be changed without opening up the speakers.
Almost any 8 ohm speaker can be driven with any receiver. Wire is wire, you can extend the wire to any reasonable length. Do not over drive them though. They will only become so loud, then excess power fed in to them will just cause them to distort, overheat, possibly even turn inside out. The Suggested Max input power suggests they are very efficient, and likely have small coil and magnet structures that can be overheated easily if , well frankly, fed to much electricity, which a large amp is quite capable of doing. High powered speakers with high basic wattage requirements can do the reverse to small amplifiers, asking for so much power to drive to reasonable volume as to tax and overheat the amp. Your issue would be the reverse of this.
The receiver just might pop them if it has any power. The fronts can take 200 Watts RMS (more but still) while the rears can't take more than 25 for VERY short periods of time. I do not recommend attaching those speakers to the rear. To an amp for your bedroom alarm system, sure, but to a receiver capable of powering the fronts? No. That said, it will work fine if you keep the power to them low.
visit a few thrift shops,or look around during nice weather when yard sales start up lt april,may,when sunny & warm again, get used well running speakers that have a lot of headroom,like 50 or a hundred wpc 8 ohms have the guy hook them up before cash exchanges hands. those thin wires break short easily & might smoke the whole set up