The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(3²) + 2π(3 x 4)
sa = 2π(9) + 2π(12)
sa = (2 x 9)π + (2 x 12)π
sa = 18π + 24π
sa = 42π

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.

(4a)(8ab) + (3a²)(5b)
(4 x 8)(a x a x b) + (3 x 5)(a² x b)
(32)(a¹⁺¹ x b) + (15)(a²b)
32a²b + 15a²b
47a²b

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 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(7 + 6)(3)
a = ½(13)(3)
a = ½(39) = \( \frac{39}{2} \)
a = 19\(\frac{1}{2}\)

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