I have connected my laptop to my TV via HDMI and my screen is shown on the TV but the full screen doesn't show

Sounds like a higher resolution being sent from your laptop than your TV is able to handle. BasAsAI is right! Just play around with the display resolutions until you find the best fit (it's not likely to be 100% perfect since you're lowering the resolution, but it'll work)
 

Antinet Chen

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Jul 23, 2015
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At the side, when you click the network and stuff, click "Devices" and click second screen. Right there, you will see 4 screens. Click the "Duplicate" button and it should work. It worked for me at least....