Question

cos8thita cos5thita- cos12thita cos9thita
/sin8thita cos5thita + cos2thita sin9thita ​

Answer 1

Step-by-step explanation:

costheta-sinthete=√2sintheta

Squaring on both sides

cos²theta+sin²theta-2costhetasintheta=2sin²theta

cos²theta-sin²theta-2costhetasintheta=0

(costheta+sintheta)(costheta-sintheta)=2costhetasintheta

(costheta+sintheta) (√2sintheta)=2costhetasintheta

costheta+sintheta=2costhetasintheta/√2sintheta

                              =√2costheta

Hence proved.

Hope this helps you out.