If (x, y) is a point on the circle x² + y² = 1 and the distance from the point P(x, y) to (-1,0) is
d = 4/5, then find the x-coordinate of point P exactly

Answer :

First, let's use the distance formula to calculate the distance between P and (-1, 0):

[tex]\begin{gathered} d=\sqrt{(y_2-y_1)^2+(x_2-x_1)^2}\\ \\ d=\sqrt{(0-y)^2+(-1-x)^2}\\ \\ \frac{4}{5}=\sqrt{y^2+x^2+2x+1} \\ (\frac{4}{5})^2=x^2+y^2+2x+1 \end{gathered}[/tex]

Since point P is on the given circle, let's subtract the equation above from the circle equation, then we solve the resulting equation for x:

[tex]\begin{gathered} x^2+y^2+2x+1-(x^2+y^2)=(\frac{4}{5})^2-(1)\\ \\ 2x+1=\frac{16}{25}-1\\ \\ 2x=\frac{16}{25}-2\\ \\ x=\frac{8}{25}-1=\frac{8}{25}-\frac{25}{25}=-\frac{17}{25} \end{gathered}[/tex]

Therefore the x-coordinate of P is -17/25.

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