Question

If y = cos θ + sin θ ; and  = 0 then number of values of θ  [0, 2π] is

Answer 1

cos Ф + sin Ф = 0
tan Ф = -1  or cot Ф = -1
tan π/4 = 1    tan 3π/4 = -1 
tan 5π/4 = 1  tan 7π/4  = -1

3π/4  and  7π/4