, or .

Take .2. find identity or counter example : csc(3pi/4 + A) = -secA

3. find identity or counter example : cosX = (cscXtanX)/(1+tan^2x)

Oh, come on! Think about it for a bit!4. find identity or counter example : (sinx)cosx = tanx

5. find identity or counter example : cos^2x = (sin^2x+cos^2x)/tan^2x + 1