SOLUTION: Equation of a Circle 7. The point (a, 8) lies on the circle defined by x^2+y^2=100. a) Explain why there are two possible values for a. Find these values. b) Use a graph to chec

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Question 189634: Equation of a Circle
7. The point (a, 8) lies on the circle defined by x^2+y^2=100.
a) Explain why there are two possible values for a. Find these values.
b) Use a graph to check that the points corresponding to both values for a are on the circle.
Thank you very much!!!!
Answer by Edwin McCravy(20060)   (Show Source): You can put this solution on YOUR website!
Equation of a Circle
7. The point (a, 8) lies on the circle defined by x^2+y^2=100.
a) Explain why there are two possible values for a.
Find these values. 

Here is why there are two possible values:

When you substitute x=a and y=8 into



you get



Then you simplify and solve for .





But then when you take the square root, there
are two square roots of 36, and so you get:



which means these two answer:

 and

b) Use a graph to check that the points corresponding to both values for a are on the circle.



You can see that both points (-6,8) and (6,8) are on
the circle 
Edwin
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