I am studying for a test and cannot figure out how to do these two questions.

1. Find the angle,θ, between the positive x-axis and a line segment joining the origin and a variable point (x, x²+1) on the graph of y=x²+1

2. Using the double angle formula sin2θ=2sinθcosθ find all θ, 0<θ<2pi,

such that sin2θ=sinθ

Thanks!