Helpp me with this one, I don’t get it

We're talking about points on the unit circle, which are coordinate pairs (x, y) that satisfy

x² + y² = 1

and the coordinates of point on the circle are governed by

x = cos(t)

y = sin(t)

If t = -35π/6, we have

x = cos(-35π/6) = cos(π/6) = √3/2

and

y = sin(-35π/6) = sin(π/6) = 1/2

because both cosine and sine have a period of 2π, which means

cos(θ) = cos(θ ± 2π) = cos(θ ± 4π) = …

and so on; in particular, we have cos(-35π/6) = cos(π/6) because

-35π/6 = π/6 - 6π

So t = -35π/6 corresponds to the point (√3/2, 1/2).

good luck on your studies! : )

david edward.