Please I need help with this resolution many trigonometric identities

What do YOU think ?
While we're happy to HELP we wont do all the work for you.
Show us what you have done and where you are having problems..

I don't know what "senx" is, but let me give some general advice about how to approach this problem.

1. Convert any tangent, cotangent, secant, and cosecant functions to their sine and cosine equivalents.
2. Simplify any fractions that are a result
3. Look for opportunities to apply simple identities such as sin^2x + cos^2x = 1, sin(2x) = 2 cos(x)sin(x), and cos(2x) = cos^2x - sin^2x = 1-2sin^2(x) = 2cos^2x - 1.
4. And simplify some more.

These steps will let you solve about 95% of all trig identity problems. Good luck!