Question

On the unit circle when 0

Answer 1

we know that
tan ∅=sin ∅/cos ∅

the value of tan ∅ will be undefined when the value of cos ∅ is zero

the value of cos ∅ is zero
when
∅=pi/2  and ∅=3*pi/2
hence 

the answer is the option
C) ∅=pi/2  and ∅=3*pi/2