# Question: given the set a x cosx 0 prove the...

###### Question details

Given the set A={ x: cos(x) = 0} prove the following:

If

D = {π2+kπ, k∈Z} then D = A. (Recall, you must show two separate statements: A ⊆ D and D ⊆ A)

Given the set A={ x: cos(x) = 0} prove the following:

If

D = {π2+kπ, k∈Z} then D = A. (Recall, you must show two separate statements: A ⊆ D and D ⊆ A)