You can use one of the sum-to-product identities.
Or, using ,
Thanks for the replys fellas. I loved doing this kind of maths a long time ago and i am now very rusty.
Could someone please verify that
i couldnt get the maths symbols to copy over hence why i had the write "pie" and "root".
this was the original question that my nephew asked me.
Id be very greatful for some help here