Find the missing coordinate of P, using the fact that P lies on the unit circle in the given quadrant. P(____, -20/29) quadrant IV

Question

Find the missing coordinate of P, using the fact that P lies on the unit circle in the given quadrant.

P(7/8,____)quadrant I

Answer 1

x^2 + y^2 = 1 to be on the unit circle

in quadrant IV x is positive

x^2 = 1-y^2 = 1- (-20/29)^2

x^2 = 1- 400/841

x= square root of (441/841)

x= 21/29

x= about .7241

P(21/29, -20/29)

x=7/8 in quadrant I, where y is also positive

y^2 = 1- x^2 = 1-(7/8)^2

= 1-49/64

= 64/64 - 49/64

= 15/64

y = sqr(15/64)

= (sqr15)/8

= about .4841

P(7/8, (sqr15)/8) which is close to P(7/8, 1/2)