Question

Find all pts on the graph of the function [[ f(x) = 2sinx + sin^2 x ]] at which the tangent line is horizontal.

Answer 1

i got ([pi/2],3) and ([3pi/2],-1) but the textbook answer is: ((pi/2) + 2n(pi), 3), ((3pi/2) + 2n(pi), -1), n is an integer

Answer 2

???

Answer 3

that's because it will repeat, since trigonometric functions are repeating

Answer 4

oh right them periods alright