I think that all of the previous posters have given you bad advice. Always, always, always check chain length when installing either a larger chainring or a larger cassette.
It's possible to ride for years with a too short chain and not even know it. Then some nice day you'll be cruising along in your big front chainring and go to shift down a cog to crest a hill. SURPRISE!!! You have just attempted to shift into the big/big with a too short chain. The weakest part to give is the derailleur arm which has twisted into your spokes. You now need a new derailleur, new rear wheel, new chain and maybe even a whole new frame. You also need a ride home.
Checking is easy so it's really stupid not to check. With your bike in the bi chainring gently try to shift onto the big cog. If it goes and you can still feel a little extra give on your derailleur arm, you're good-to-go. It it doesn't, you need a longer chain.