Youngkwon C. answered 11/29/15
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Hi Heer,
For a point on the circle of which radius is r and
angle measured counterclock-wise from the x-axis is θ,
its x-coordinate and y-coordinate are given by r·cosθ and r·sinθ, respectively.
For the special case of the unit circle,
its x-coordinate and y-coordinate are given by cosθ and sinθ, respectively.
When θ = 30°, (x, y) = (cos(30°), sin(30°)) = (√3/2, 1/2).
When θ = 45°, (x, y) = (cos(45°), sin(45°)) = (√2/2, √2/2).
When θ = 60°, (x, y) = (cos(60°), sin(60°)) = (1/2, √3/2).