Question: equation of a circle
Answer: (x-h)²+(y-k)²=r²
==================================================
Question: completing the square
Answer: a process for completing an unfinished quadratic equation
==================================================
Question: concentric circles
Answer: circles that share a center but have different radii
==================================================
Question: arc length
Answer: the distance between two points on a circle
==================================================
Question: radian
Answer: the measure of an intercepted arc of a central angle whose length is equal to the radius of the circle
==================================================
Question: area of a sector
Answer: the 2-dimensional space inside the pie shaped area bound by a central angle
==================================================