If cos^2theta -sin^2theta=1/3, value of (cos^4theta-sin^4theta+1) is:

(A) 4/3

(B) 5/3

• let, theta=x;
  Now,(cos^4x-sin^4x+1)=[{(cos^2x -sin^2x)*(cos^2x+sin^2x)} +1]=[{(1/3)*(1)}+1]=
  =(4/3)..
  So, the correct answer is OPTION (A) 4/3
• 12 years agoHelpfull: Yes(14) No(0)