Your boss intentionally asks you tasks but he does not offer the necessary requirements to perform these tasks, what is your reaction?

Writting a formal report to the manager explains the necessary requirements to do my job

Adapt.

Normal task shall have included requirements specified on it, but sometimes if not well defined and complete, you have to analyze and seek for it and be open to discuss with the boss.

generate the requiremnts your slef u must have resources dont look at the boss for every thing. i have been in such shoes and i came up with task completion and my boss was very happy with it.

I will arranged the necessry requirement onbehalf of my knowladge to do the task but the reuiremnts are not fulfill then i will discuss with boss open mindly.

this is a tough question especially for someone who works in the filed 

normally i will discuss with him that this job can not be done or it would be done unprofessionally if the requirements is not fulfilled. if he refuse saying that he knows best (most of them say :) ) then at that time my decision will depend on the situation either i will do it but it's all his call, or i will refuse it completely if the task endanger others or might cause legal and moral issues.

If you are capable to think well, keep proactive approach then just start task and gather basic information and then sit in front of your boss for further requirements.