Which of the following could not be points on the unit circle?
a.(0.8, -0.6)
b.(-2/3,√ 5/3)
c.(√ 3/2, 1/3)
d.(1,1)

Question

Which of the following could not be points on the unit circle?
a.(0.8, -0.6)
b.(-2/3,√ 5/3)
c.(√ 3/2, 1/3)
d.(1,1)

jim_thompson5910 · Answer

All points (x,y) on the unit circle satisfy the equation $\large x^2 + y^2 = 1$

jim_thompson5910 · Answer

The "unit" refers to the radius being r = 1

jim_thompson5910 · Answer

Looking at choice A, we see that x = 0.8 and y = -0.6

$$\Large x^2 + y^2 = 1$$
$$\Large (0.8)^2 + (-0.6)^2 = 1$$
$$\Large 0.64+0.36 = 1$$
$$\Large 1 = 1$$

So (0.8,-0.6) is definitely on the unit circle

anonymous · Answer

I was guessing b and c?

jim_thompson5910 · Answer

you will do the same basic steps for choices B through D

anonymous · Answer

I mean A and D

jim_thompson5910 · Answer

well I just showed that A is on the unit circle. So choice A is out. They want points that are NOT on the unit circle.

jim_thompson5910 · Answer

you need to find points (x,y) that make x^2 + y^2 = 1 false

anonymous · Answer

Alright got you! thanks

jim_thompson5910 · Answer

no problem