If the point P(13/16,y) is on the unit circle in quadrant IV, then y=

Answer 1

Hi Antonia T.,

A unit circle has a radius of 1, so r = 1. The point P(13/16, y) in the IV quadrant will have a positive x-value and a negative y-value. Using the Pythagorean theorem we know that, x² + y² = r², in a Cartesian coordinate system. We can solve for y by rearranging the formula, r² - x² = y², or y = ±√(r² - x²).

y = ±√(r² - x²)

y = ±√([1]² - [13/16]²)

y = ±√(1 - 169/256)

y = ±√(87/256)

y = ±√(87)/16, we choose the negative for quadrant IV.

y = -√(87)/16

I hope this helps, Joe.