Question

Which Of the following could not be points on the units circle ?

Answer 1

Answer:

Options a and c

Step-by-step explanation:

A unit circle is one which has origin as centre and radius as 1.

The equation of the unit circle would be

$x^2+y^2 =1$

Thus we find that any point satisfying the above equation lies on the unit circle

Let us try the given points one by one

a) $(0.8)^2+(-0,6)^2 =1$. Hence lies on the circle

b) (1,1)

Cannot lie on circle since $1^2+1^2 \neq 1$

c) $(\frac{-2}{3} ,\frac{\sqrt{5} }{3} )\\(\frac{-2}{3})^2+(\frac{\sqrt{5} }{3} )^2 =1$. Hence lies on the circle

d) $(\frac{\sqrt{3} }{2} ,\frac{1}{3} )\\(\frac{\sqrt{3} }{2})^2+(\frac{1}{3} )^2\\\neq 1$

Hence does not lie on the circle

Only option A,C are right

Answer 2

answer A , that could not be point