The formula for area is πr². Radius is circle \( \frac{diameter}{2} \):

r = \( \frac{d}{2} \)
r = \( \frac{6}{2} \)
r = 3
a = πr²
a = π(3²)
a = 9π

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

8a x 5b = (8 x 5) (a x b) = 40ab

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

y² - 3y - 18 = 0
(y + 3)(y - 6) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y + 3) or (y - 6) must equal zero:

If (y + 3) = 0, y must equal -3
If (y - 6) = 0, y must equal 6

So the solution is that y = -3 or 6

For parallel lines with a transversal, the following relationships apply:

• angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°)
• alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°)
• all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other
• same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°)

Applying these relationships starting with c° = 25, the value of x° is 155.

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 12 as well and sum (Inside, Outside) to equal 7. For this problem, those two numbers are 3 and 4. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 7y + 12
y² + (3 + 4)y + (3 x 4)
(y + 3)(y + 4)