Question

Cos4A-sin4A is equal

Answer 1

❤❤Here is your answer ✌ ✌

$\huge {\red {\bold {Answer}}}$
L.H.S.  
  sin4 a-cos4a 

 =>(sin2a)2 -(cos2a)2     
=>(sin2a-cos2a)(sin2a+cos2a)                =>(sin2a-1+sin2a) 1       

=>(2sin2a-1) ✔✔