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 Acute angle  Any angle between 0° and 90° .
 Adjacent side  The side of a right triangle that is next to the reference angle. (Not hypotenuse)
 Angle  1. The shape made by two straight lines meeting in a point. 2. The space between those lines. 3. The measurement of that space in degrees or radians.
 Angle of turn  The angle created when a line of work is turned. The angle of turn is formed between where the original line would have gone (if it had not turned) and the line going in the new direction.
 Arc function (also called inverse function)  The function used to find the degrees of an angle when the ratio of the sides of the angle is known. The six arc functions are: arc sine, arc cosine, arc tangent, arc cosecant, arc secant, and arc cotangent.
 Arc  A curved line whose points are equal distances from a single point.
 Arc length  The length of a curved line.
 Area  The measurement of a surface, expressed in square units.
 Bisecting line  A line which divides an object or shape into two equal parts.
 Central angle  An angle whose vertex is located at the center of a circle.
 Center length  The distance of the straight line or piece of material between the arcs of an offset.
 Center Mark Back  The distance used in marking and cutting a miter from the center line.
 Chord  A straight line from one point on a circle to another point on the circle. The longest chord of a circle is the diameter.
 Circle  A curved line in a plane that encloses a space. Every point on the curved line is exactly the same distance from the center point.
 Circumference  The distance around a circle.
 Common side of two triangles  A line that is shared by two triangles. It can be the hypotenuse of one triangle and the leg of the other.
 Compass  A tool used to draw circles and curved lines.
 Complementary angles  Two angles whose sum equals 90° . The two lesser angles of a right triangle are always complementary.
 Conversion  For fractions : The process of changing the numerator and the denominator of a fraction to make a new fraction of equal value. Example: 1/2 to 2/4. For units of measurement : The Process of changing a unit of measurement to a different unit of measurement while keeping the value the same. Example: 2 feet to inches, 2 feet = 24 inches.
 Cosecant  One of the functions of an angle. It is found by dividing the length of the hypotenuse of a right triangle by the length of the opposite side of a reference angle.
 Cosine  One of the functions of an angle. It is found by dividing the length of the adjacent side of a reference angle by the length of the hypotenuse.
 Cotangent  One of the functions of an angle. It is found by dividing the length of the adjacent side of a reference angle by the length of the opposite side of a reference angle.
 Equilateral triangle  A triangle with equal sides and equal angles.
 Formula  An equation that follows a rule. Formulas contain variables that when replaced by numbers, allow unknown quantities to be found. An example of a formula is the Pythagorean Theorem, a squared + b squared = c squared.
 Fraction  A number that expressed a portion of a whole. The denominator of a fraction represents the number of the portions the whole has been divided into, and the numerator expresses the number of the portions measured. The fraction 1/4 could be stated as 1 our of 4 parts of the whole.
 Fractions, ruler  The portions into which the English units of measurement such as inches can be divided  for example, halves, fourths, eighths, sixteenths, and thirtyseconds.
 Functions of an angle  The name of a particular ratio of the sides of a right triangle. The name of the function will depend on which side is divided into which side. There are six possible ways to divide the sides of a right triangle into each other. There are six functions for each angle. The names are: sine, cosine, tangent, cosecant, secant, and cotangent.
 Functions table  A table of the functions of angles. This table allows one to find either the function of an angle or the degree of an angle.
 Hypotenuse  The longest side of a right triangle. It is always located directly across from the right angle.
 Improper fraction  A fraction which is equal to one or more than one.
 Inside arc  The shortest arc of a turn.
 Inverse  A term which means turned upside down. For example the ratio top/bottom is expressed inversely as bottom/top.
 Isosceles right triangle  A 45° right triangle. There is only one right triangle that has two equal legs  the 45° right triangle.
 Isosceles triangle  A triangle that has two equal legs and two equal angles.
 Legs of a right triangle  The sides of a right triangle other than the hypotenuse.
 Level  Even, flat, not having any part higher or lower than another part.
 Lowest term fraction  A fraction which can not be reduced to a lower term.
 Obtuse angle  An angle between 90° and 180° .
 Offset  To change the direction of a line by making a turn and correcting back to the original direction by making another turn. Also, offset is the term used to identify such a turn.
 Offset box  An imaginary box which is used when drawing thumbnail sketches to calculate offsets.
 Opposite side  The side of a right triangle that is opposite the reference angle.
 Outside arc  The longest arc of a turn.
 Parallel lines  Lines that are in the same plane and always the same distance apart.
 Perpendicular  a 90° angle between two lines. It is also called a right angle.
 Pi (¼ )  The ratio of the circumference of a circle to its diameter. It is the whole number 3 and a decimal fraction that has endless decimal places. We usually round it off to four decimal places (3.1416) for our work.
 Plane  A flat, level or even surface.
 Plumb  Exactly Vertical. A line that is perpendicular to ground level is plumb.
 Point of tangency  The point where a circle and a tangent line touch.
 Pythagorean theorem  The formula a squared + b squared = c squared, which signifies that the square of the length of the hypotenuse of a right triangle equals the sum of the squares of the length of the other two sides.
 Secant  One of the functions of an angle. It is found by dividing the length of the hypotenuse of a right triangle by the length of the adjacent side of a reference angle.
 Sector  A part of a circle which includes two radii connected by the arc.
 Second  A division of the minutes of a degree. There are 60 seconds in each minute of a degree.
 Simple offset  A procedure by which a center line is moved up, down, or over to reach a new path going in the same direction. A simple offset uses two same angle turns.
 Sine  One of the functions of an angle. It is found by dividing the length of the opposite side of a reference angle by the length of the hypotenuse of the right triangle.
 Square root  A factor of a number which when squared produces that number. A square root multiplied by itself equals the number under the square root symbol.
 Square  The product of a number multiplied by itself.
 Straight angle  An angle of 180° (in other words, a straight line).
 Zero degree angle  An angle with no space between the two lines. In other words, the two lines are occupying the same space. The difference between a straight angle and a zero degree angle is that the vertex is in the middle of the line for a straight angle but at the end of the line for a zero degree angle.
