原式=∫[1-1/(2sin²x+cos²x)]dx
=∫dx - ∫[sec²x/(2tan²x+1)]dx
=∫dx - ∫1/[(√2tanx)²+1)]d(tanx)
=∫dx - √2/2* ∫1/[(√2tanx)²+1)]d(√2tanx)
=x - ∫dx - √2/2*arctan(√2tanx)+c