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 x 2b = (4 x 2) (a x b) = 8ab

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(8 + 2)(3)
a = ½(10)(3)
a = ½(30) = \( \frac{30}{2} \)
a = 15

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 perimeter of a triangle is the sum of the lengths of its sides:

p = x + y + z
p = 13cm + 10cm + 14cm = 37cm

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 4 x 9) + (2 x 9 x 8) + (2 x 4 x 8)
sa = (72) + (144) + (64)
sa = 280