I don’t know how to do this one.

Part (a)

The unit circle is centered at (0,0). This point is the origin.

The radius of the unit circle is 1

The term "unit" means "one", which describes the radius length.

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Part (b)

The equation of the unit circle is x^2+y^2 = 1

The general equation of any circle is (x-h)^2+(y-k)^2 = r^2

In this case, the unit circle has center (h,k) = (0,0) and radius r = 1.

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Part (c)

The following four points are on the unit circle

As shown below in the diagram. The idea is to plug each given coordinate into the equation from part (b), and solve for the missing variable.

For example, if we know x = 1, then...

x^2+y^2 = 1

1^2+y^2 = 1

1+y^2 = 1

y^2 = 1-1

y^2 = 0

y = sqrt(0)

y = 0

Meaning x = 1 leads to y = 0. So (x,y) = (1,0) is one point on the circle. The other parts are handled in a similar fashion.

5/12, or 5: 12

step-by-step explanation: