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 triangle is equal to ½ base x height:

a = ½bh
a = ½ x 7 x 5 = \( \frac{35}{2} \) = 17\(\frac{1}{2}\)

A parallelogram is a quadrilateral with two sets of parallel sides. Opposite sides (a = c, b = d) and angles (red = red, blue = blue) are equal. The area of a parallelogram is base x height and the perimeter is the sum of the lengths of all sides (a + b + c + d).

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.

(7a)(3ab) + (3a²)(6b)
(7 x 3)(a x a x b) + (3 x 6)(a² x b)
(21)(a¹⁺¹ x b) + (18)(a²b)
21a²b + 18a²b
39a²b

To solve this equation, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

-8a(a - x)
-8(1)(1 + 7)
-8(1)(8)
(-8)(8)
-64