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).

The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

y² - 10y + 9 = 0
(y - 1)(y - 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y - 1) or (y - 9) must equal zero:

If (y - 1) = 0, y must equal 1
If (y - 9) = 0, y must equal 9

So the solution is that y = 1 or 9

According to the Pythagorean theorem, the hypotenuse squared is equal to the sum of the two perpendicular sides squared:

c² = a² + b²
c² = 6² + 4²
c² = 36 + 16
c² = 52
c = \( \sqrt{52} \)

The area of a trapezoid is one-half the sum of the lengths of the parallel sides multiplied by the height:

a = ½(b + d)(h)
a = ½(2 + 5)(3)
a = ½(7)(3)
a = ½(21) = \( \frac{21}{2} \)
a = 10\(\frac{1}{2}\)

The formula for circumference is circle diameter x π:

c = πd
c = 4π