McGraw Hill Glencoe Algebra 2, 2012
MH
McGraw Hill Glencoe Algebra 2, 2012 View details
5. Law of Cosines
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Exercise 50 Page 828

Use the discriminant of the equation by rewriting it in the form Ax^2+Bxy+Cy^2+Dx+Ey+F=0.

Circle

Practice makes perfect

We want to state whether the graph of the given equation is a parabola, a circle, an ellipse, or a hyperbola. To do so, we will rewrite it in the form Ax^2+ Bxy+ Cy^2+ Dx+ Ey+ F=0. Then we can determine its discriminant. Recall that missing terms have coefficient 0. x^2 + y^2 - 8x - 6y + 5 = 0 ⇕ 1x^2 + 0xy + 1y^2 + ( - 8)x + ( - 6)y + 5=0The discriminant of the equation can be found by evaluating B^2-4 A C. This will tell us which type of conic section we might have.

Discriminant Conic Section
B^2-4AC<0; B=0 and A=C Circle
B^2-4AC<0; either B≠ 0 or A≠ C Ellipse
B^2-4AC=0 Parabola
B^2-4AC>0 Hyperbola

Let's calculate the discriminant of our equation.

B^2-4AC
0^2-4( 1)( 1)
â–¼
Simplify
0-4(1)(1)
0 - 4
- 4

The discriminant is less than 0 and A = C, so the graph of the equation is a circle.