If 4 cos 2 x° - 1 = 0 and 0 x 90, find (i) x (ii) sin 2 x° + cos 2 x° (iii) cos 2 x° - sin 2 x°.

(i) Given, Since, x is an acute angle. . ⇒ cos x° = cos 60° ⇒ x = 60. Hence, x = 60. (ii) Substituting value of x in sin 2 x° + cos 2 x° we get : Hence, sin 2 x° + cos 2 x° = 1. (iii) Substituting value of x in cos 2 x° - sin 2 x° we get : Hence, cos 2 x° - sin 2 x° = .