To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce -30 as well and sum (Inside, Outside) to equal -1. For this problem, those two numbers are -6 and 5. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² - y - 30
y² + (-6 + 5)y + (-6 x 5)
(y - 6)(y + 5)

A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

A monomial contains one term, a binomial contains two terms, and a polynomial contains more than two terms.

A quadrilateral is a shape with four sides. The perimeter of a quadrilateral is the sum of the lengths of its four sides.

The sum of the interior angles of a triangle is 180°:
180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 66° - 48° = 66°