use lagrange multipliers to find the minimum distance from the curve or surface to the indicated point…

use lagrange multipliers to find the minimum distance from the curve or surface to the indicated point. (round your answer to two decimal places.)\ncurve\ncircle: $(x - 2)^2 + y^2 = 2$\npoint\n$(0, 10)$
Answer
Explanation:
Step1: Set up the distance formula and constraint
The distance formula from a point ((x,y)) to ((0,10)) is (d=\sqrt{(x - 0)^2+(y - 10)^2}). To simplify calculations, we can minimize (f(x,y)=x^{2}+(y - 10)^{2}) (since minimizing (d) is equivalent to minimizing (d^{2})). The constraint is (g(x,y)=(x - 2)^{2}+y^{2}-2=0). By the method of Lagrange multipliers, (\nabla f=\lambda\nabla g). We have (\nabla f=\left\langle 2x,2(y - 10)\right\rangle) and (\nabla g=\left\langle 2(x - 2),2y\right\rangle). So, the system of equations is: (\begin{cases}2x=\lambda\times2(x - 2)\2(y - 10)=\lambda\times2y\(x - 2)^{2}+y^{2}=2\end{cases}) From the first equation (2x = 2\lambda(x - 2)), we get (x=\lambda(x - 2)), so (\lambda=\frac{x}{x - 2}(x\neq2)). From the second equation (2(y - 10)=2\lambda y), we get (\lambda=\frac{y - 10}{y}(y\neq0)). Then (\frac{x}{x - 2}=\frac{y - 10}{y}), cross - multiplying gives (xy=(x - 2)(y - 10)), which expands to (xy=xy-10x-2y + 20), so (10x+2y=20) or (y = 10 - 5x).
Step2: Substitute (y = 10 - 5x) into the constraint equation
Substitute (y = 10 - 5x) into ((x - 2)^{2}+y^{2}=2): ((x - 2)^{2}+(10 - 5x)^{2}=2) Expand: (x^{2}-4x + 4+100-100x + 25x^{2}=2) Combine like terms: (26x^{2}-104x + 102 = 0) Divide by 2: (13x^{2}-52x + 51=0) Using the quadratic formula (x=\frac{52\pm\sqrt{52^{2}-4\times13\times51}}{2\times13}=\frac{52\pm\sqrt{2704 - 2652}}{26}=\frac{52\pm\sqrt{52}}{26}=\frac{52\pm2\sqrt{13}}{26}=2\pm\frac{\sqrt{13}}{13}) If (x = 2+\frac{\sqrt{13}}{13}), then (y=10-5(2+\frac{\sqrt{13}}{13})=10 - 10-\frac{5\sqrt{13}}{13}=-\frac{5\sqrt{13}}{13}) If (x = 2-\frac{\sqrt{13}}{13}), then (y=10-5(2-\frac{\sqrt{13}}{13})=10 - 10+\frac{5\sqrt{13}}{13}=\frac{5\sqrt{13}}{13})
Step3: Calculate the distance
The distance formula (d=\sqrt{x^{2}+(y - 10)^{2}}) For the point ((x = 2-\frac{\sqrt{13}}{13},y=\frac{5\sqrt{13}}{13})) (d=\sqrt{(2-\frac{\sqrt{13}}{13})^{2}+(\frac{5\sqrt{13}}{13}-10)^{2}}) (=\sqrt{4-\frac{4\sqrt{13}}{13}+\frac{13}{169}+\frac{325}{169}-\frac{100\sqrt{13}}{13}+100}) (=\sqrt{104-\frac{104\sqrt{13}}{13}+\frac{338}{169}}) Another way is to use the geometric interpretation. The center of the circle (C=(2,0)) and radius (r=\sqrt{2}). The distance between ((0,10)) and ((2,0)) is (D=\sqrt{(2 - 0)^{2}+(0 - 10)^{2}}=\sqrt{4 + 100}=\sqrt{104}) The minimum distance (d=\sqrt{104}-\sqrt{2}\approx10.20 - 1.41=8.79)
Answer:
(8.79)