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| Find the tangent of a circle x^2+y^2=25 on point (4,3) Solution : Prove that point (4,3) lies in a circle x^2+y^2=25 substitute (4,3) to a circle equation 4^2+3^2=16+9=25 right thus this point should lie in that circle. The tangent line to the circle at point (4,3) should be : x1*x+y1*y=25 where (x1,y1)=(4,3) at a circle 4*x+3*y=25 is the tangent line you look for. |
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