limx-->pi/2^+ (-8/cosx)

Question

limx-->pi/2 (-8/cosx)

evaluate the right hand limit

I keep getting -8/0⁺ (since cos(pi/2) is approaching zero from the right hand side) and keep getting negative infinity as my answer, but correct answer is positive infinity. Can someone please explain why this is?

Answer 1

Again, there is no limit.

cos (90+x) = -cos (90-x)

This should give you the answer to the problem.