Question

If the point ( x , √3/2) is on the unit circle, what is x?

A. √3/2

B. 1/2

C. - √3/2

D. 2/√3

Answer 1

B. 1/2

Explanation:

This problem involves the use of the Pythagorean theorem. In the unit circle, the hypotenuse of any right triangle formed is 1 while the coordinates of the point are then the two legs that make up the triangle.

a = 1 (given)

b = √3/2 (given)

a² = b² + c² (Pythagorean Theorem)

1² = (√3/2)² + c² (Substitute information)

Now, we need to solve for c

1 = (3/4) + c² (square the hypotenuse and one of the legs)

1 - (3/4) = (3/4) + c² - (3/4) (subtract 3/4 on both sides)

1/4 = c² (combine like terms)

√(1/4) = √(c²) (square root both sides)

√1 / √4 = c (square root both sides)

1/2 = c (final answer)

Therefore the other leg of the right triangle is 1/2, this also means that the other coordinate, or x, is 1/2, so the answer is B. 1/2.