IF tan2A = 1 +2 tan2B, then the value of √2 cosA – cosB is.

Sincetan²A=1+2tan²B

adding 1 to both sides we get:

1+tan²A=2+2tan²B

⇒sec²A=2sec²B

⇒2cos²A=cos²B

⇒2√cosA=cosB.

Assuming cos(A), cos(B) both ≥ 0. In other words,

2√cosA−cosB=0