Answer:
D. [0,pi/2]
Step-by-step explanation:
when Ф = 0 in radian
r²= 4cos (2(0))
r² = 4 * 1
r² = 4
∴ r = √4 = 2
r = 2.
when Ф = π/2 in radian
r²= 4cos (2(π/2))
r² = 4 * -1
r² = -4
∴ r = 0
368
ur correct it's A. trust me u look up all the definitions to the other than A. they gonna be wrong already looked em all up
