Fill in the blank to complete the fundamental trigonometric

Fill in the blank to complete the fundamental trigonometric identity. cos (pi / 2 - u) = Fill in the blank to complete the fundamental trigonometric identity. cos (-u) = Fill in the blank to complete the fundamental trigonometric identity. sec(-u) =

Solution

5)

cos(pi/2 - u ) = sin u

7)

sec(-u) = sec u

As sec is reciprocal of cos

and cos(-u)= cos u