# Question Video: Simplifying Trigonometric Expressions Using Double-Angle Identities Mathematics • Second Year of Secondary School

Which of the following expressions is equivalent to cosΒ² (π/4) β sinΒ² (π/4)? [A] cos (π/4) [B] 2 cos (π/4) [C] cos (π/2) [D] sin (π/2) [E] 2 sin (π/4)