Module 3 Vocabulary
Adjacent angles: Any two angles with a common side. For example, ∠BAC is adjacent to ∠CAD because they share ray AC. (Figure 1)
Angles at a point: Angles formed by three or more rays (sides) that share a vertex (the point where rays meet) and whose measures sum to 360 degrees. For example, m∠BAC + m∠CAD + m∠DAB = 360°. (Figure 2) Angles on a line: Two adjacent angles that form a line and whose measures sum to 180 degrees. For example, m∠ABC + m∠CBD = 180°. (Figure 3) Circle: The set of all points in the plane whose distance from the point C, the center, is equal to r, the radius. (Figure 4 and Figure 5) Circumference: The distance around a circle. The formula to calculate the circumference is C = πd, where C represents the circumference of the circle and d represents the diameter. Coefficient: A constant factor (not to be confused with a constant) in a variable term. For example, in the term 4m, 4 is the coefficient, and it is multiplied by the variable, m. Diameter: The length across a circle from one side to the other passing through the center. For example, in Figure 1, the length of segment AB is the diameter of circle C. Distributive property: Allows the numbers in a multiplication problem to be distributed into partial products (i.e., partial answers). The partial products can then be added together to find the product, or the answer to the original multiplication problem. For example, 3(x + 7) = (3x) + (3 · 7) = 3x + 21. Equation: A statement indicating that two expressions are equal (e.g., 3 × 4 = 6 × 2). Equivalent expressions: Expressions that have the same value. For example, 2 × 6 and 4a (when a = 3) are equivalent expressions. Expression: A group of numbers, symbols, and operators (e.g., + and −) with no equal sign that represents a single value. For example, 2 × 4 and 9(x + 1) are expressions. Expression in standard form: An expression where all like terms are collected. For example, 2x + 3x + 5 is an expression; however, to write it in standard form, you must combine the like terms 2x and 3x. The equivalent expression 5x + 5 is written in standard form. Inequality: A statement comparing expressions that are unequal or not strictly equal. The symbol used to compare the expressions reveals the type of inequality: < (less than), ≤ (less than or equal to), > (greater than), ≥ (greater than or equal to), or ≠ (not equal). Like terms: Terms that have the same variable to the same power. For example, 3x and −8x are like terms because they both have a variable of x and a common power of 1. However, 3x and −8y are not like terms because they do not have the same variable. Number sentence: A statement indicating that two numerical expressions are equal (e.g., 8 - 2 + 2 = 8). Opposites: Numbers that are the same distance from zero on the number line but on different sides of zero (e.g., −3 and 3). Pi: The value of the ratio of a circle’s circumference to its diameter, that is, π = circumference diameter. Radius: The length of any line segment connecting the center point of a circle to any point that lies on the circle. For example, in Figure 5, the length of segment CB is the radius of circle C. Ray: Part of a line with an initial point at one end and continuing indefinitely in the other direction. Surface area: The total area that the surface (outside) of a three-dimensional object occupies, measured in square units. Volume: The amount of space enclosed inside a three-dimensional object, such as a cube or a prism, measured in cubic units. Term: Part of an expression that can be added to or subtracted from the rest of the expression. In the expression 7g + 8h + 3, the terms are 7g, 8h, and 3. Vertical angles: The pair of opposite angles created when two lines intersect. The angles have the same measures. For example, m∠DCF = m∠GCE. (Figure 6)
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