Having trouble with this integer below....?

Question

(4/3)(3^1/2 )
∫ [1/(16 + x^2)] dx =
0

possible solutions....

a. π/24

b. π/12

c. π/6

d. 2π/9

e. π/4

f. π/3

g. π/2

h. π

i. none of these

Answer 1

∫dx/(16 + x^2) = 4∫d(x/4)/(16 + 16(x/4)^2) =
∫d(x/4)/(1 + (x/4)^2) =
arctan(x/4) [from 0 to 4/√3] =
arctan(1/√3) = π/6