Question

On a unit circle, the vertical distance from the x-axis to a point on the perimeter of the circle is twice the horizontal

distance from the y-axis to the same point. What is sine?

Answer 1

The answer would be C.

Explanation:

Answer 2

(2/5)√5 ≈ 0.894427

Explanation:

You require the y-coordinate of the point that satisfies two equations:

x^2 +y^2 = 1

y = 2x

Substituting for x, we have ...

(y/2)^2 +y^2 = 1

y^2(5/4) = 1

y^2 = 4/5

y = (2/5)√5 ≈ 0.894427

The sine of the angle is (2/5)√5 ≈ 0.894427.