Answer:
The point of intersection is:
![\displaystyle \left(\frac{6\sqrt{5}}{5}, \frac{3\sqrt{5}}{5}+5\right)\approx \left(2.68, 6.34)](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cleft%28%5Cfrac%7B6%5Csqrt%7B5%7D%7D%7B5%7D%2C%20%5Cfrac%7B3%5Csqrt%7B5%7D%7D%7B5%7D%2B5%5Cright%29%5Capprox%20%5Cleft%282.68%2C%206.34%29)
Step-by-step explanation:
We want to find the point in QI at which the line with the equation:
![y=0.5x+5](https://tex.z-dn.net/?f=y%3D0.5x%2B5)
Intersect a circle with a radius of 3 and a center of (0, 5).
First, write the equation of a circle. The equation for a circle is given by:
![(x-h)^2+(y-k)^2=r^2](https://tex.z-dn.net/?f=%28x-h%29%5E2%2B%28y-k%29%5E2%3Dr%5E2)
Where (<em>h, k</em>) is the center and <em>r</em> is the radius.
Since our center is (0, 5), <em>h</em> = 0 and <em>k</em> = 5. The radius is 3. So, <em>r</em> = 3. Substitute:
![(x-0)^2+(y-5)^2=(3)^2](https://tex.z-dn.net/?f=%28x-0%29%5E2%2B%28y-5%29%5E2%3D%283%29%5E2)
Simplify:
![x^2+(y-5)^2=9](https://tex.z-dn.net/?f=x%5E2%2B%28y-5%29%5E2%3D9)
At the point where the two equations intersect, its <em>x-</em>coordinate and <em>y-</em>coordinate will be the same. Therefore, we can substitute the equation of the line into the equation of the circle and solve for <em>x</em>. So:
![x^2+((0.5x+5)-5)^2=9](https://tex.z-dn.net/?f=x%5E2%2B%28%280.5x%2B5%29-5%29%5E2%3D9)
Simplify:
![x^2+(0.5x)^2=9](https://tex.z-dn.net/?f=x%5E2%2B%280.5x%29%5E2%3D9)
Square:
![x^2+0.25x^2=9](https://tex.z-dn.net/?f=x%5E2%2B0.25x%5E2%3D9)
Combine like terms:
![\displaystyle 1.25x^2=\frac{5}{4}x^2=9](https://tex.z-dn.net/?f=%5Cdisplaystyle%201.25x%5E2%3D%5Cfrac%7B5%7D%7B4%7Dx%5E2%3D9)
Solve for <em>x: </em>
<em />
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Note that since we are looking for the point of intersection in QI, <em>x</em> should be positive. So, we can ignore the negative answer.
To find the <em>y-</em>coordinate, substitute the <em>x-</em>value back into either equation. Using the linear equation:
![\displaystyle y=0.5\left(\frac{6\sqrt{5}}{5}\right)+5=\frac{3\sqrt{5}}{5}+5\approx 6.34](https://tex.z-dn.net/?f=%5Cdisplaystyle%20y%3D0.5%5Cleft%28%5Cfrac%7B6%5Csqrt%7B5%7D%7D%7B5%7D%5Cright%29%2B5%3D%5Cfrac%7B3%5Csqrt%7B5%7D%7D%7B5%7D%2B5%5Capprox%206.34)
So, the point of intersection in QI is:
![\displaystyle \left(\frac{6\sqrt{5}}{5}, \frac{3\sqrt{5}}{5}+5\right)\approx \left(2.68, 6.34)](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cleft%28%5Cfrac%7B6%5Csqrt%7B5%7D%7D%7B5%7D%2C%20%5Cfrac%7B3%5Csqrt%7B5%7D%7D%7B5%7D%2B5%5Cright%29%5Capprox%20%5Cleft%282.68%2C%206.34%29)