Question

The last of my points. Given the unit circle, what is the value of y? This my last question.

Answer 1

y = -
`(√(111) )/(20)`

Explanation:

using Pythagoras' identity in the right triangle formed by the radius 1 and the given point, then

y² + (-
`(17)/(20)` )² = 1²

y² +
`(289)/(400)` = 1

y² = 1 -
`(289)/(400)` =
`(111)/(400)` ( take square root of both sides )

y = ±
`\sqrt{(111)/(400) }` = ±
`(√(111) )/(20)`

since the point is in the third quadrant then y < 0

y = -
`(√(111) )/(20)`