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The equation of a circle in standard form is 2(x−h)²+(y−k)²=r² where h and k are the coordinates of the center, and r is the _______.

a) slope
b) radius
c) diameter
d) circumference

User Dynamitem
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1 Answer

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Final answer:

The 'r' in the standard form equation of a circle 2(x-h)²+(y-k)²=r² represents the radius of the circle, not the slope, diameter, or circumference. The correct answer is option b.

Step-by-step explanation:

The equation of a circle in standard form is given as 2(x−h)²+(y−k)²=r² where h and k are the coordinates of the center of the circle, and r represents the radius of the circle. This equation clearly defines a circle with a constant distance from the center to any point on its perimeter, which is the defining characteristic of a circle as opposed to other shapes such as ellipses, where the sum of the distances from two special points (foci) to any point on the curve is constant. A circle is a special case of an ellipse in which the two foci coincide.

Understanding this equation helps to remember that the radius is a crucial element in the circle's geometry. It helps to deduce other properties like area and circumference. The area of a circle is given by πr² and the circumference is 2πr, where π is approximately 3.14159. While the radius is half the diameter, it is also used to calculate the circle's arc length when a radius sweeps through a given angle, indicating its pervasive role in circular motion and related geometric and physical calculations.

The correct option for what r represents in the given circle equation is (b) radius.

User Belhor
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