The value of y on the unit circle is y =-3/5
<h3>What is a circle?</h3>
A circle is defined as the locus of a point such that it is equidistant from a fixed point.
The equation of a circle with center at the origin is given by x² + y² = r² where r = radius of circle
<h3>What is a unit?</h3>
A unit circle is a circle with radius, r = 1.
So, the equation of a unit circle is x² + y² = 1
<h3>How to find the value of y on the unit circle?</h3>
Given that the point P(-4/5, y) lies on the unit circle, and P is int he third quadrant, making y subject of the formula in the equation for unit circle, we have
y = ±√(1 - x²)
Substituting x = -4/5 into the equation, we have
y = ±√(1 - x²)
y = ±√(1 - (-4/5)²)
y = ±√(1 - 16/25)
y = ±√[(25 - 16)/25]
y = ±√[9/25]
y = ±3/5
Now, given that P is in the third quadrant, it implies that y is negative. so, y = -3/5
So, the value of y on the unit circle is y =-3/5
Learn more about unit circle here:
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