4.7 Angles and Angle Measurement
Unit Goals
- Students learn to draw and identify points, rays, segments, angles, and lines, including parallel and perpendicular lines. Students also learn how to use a protractor to measure angles and draw angles of given measurements, and identify acute, obtuse, right, and straight angles in two-dimensional figures.
Section A Goals
- Draw and identify points, lines, rays, segments, and parallel and intersecting lines in geometric figures.
- Recognize that angles are formed wherever two rays share a common endpoint and identify angles in two-dimensional figures.
Section B Goals
- Recognize that angles can be measured in degrees, and can be found using addition and subtraction.
- Use a protractor to measure and draw angles, and recognize that perpendicular lines meet or cross at a right angle.
Section C Goals
- Draw and identify acute, obtuse, right, and straight angles in two-dimensional figures.
- Write equations to represent angle relationships and reason about and find unknown measurements.
Glossary Entries
- acute angleAn angle that measures less than 90 degrees.
- angleA figure made up of two rays that share the same endpoint.
- common denominatorThe same denominator in two or more fractions. For instance, \(\frac{1}{4}\) and \(\frac{5}{4}\) have a common denominator.
- composite numberA whole number with more than 1 factor pair.
- denominatorThe bottom part of a fraction that tells how many equal parts the whole was partitioned into.
- dividendThe number being divided. For example, when 37 is divided by 5, we call 37 the dividend.
- equivalent fractionsFractions that have the same size and describe the same point on the number line. For example, \(\frac{1}{2}\) and \(\frac{2}{4}\) are equivalent fractions.
- factor pair of a whole numberA pair of whole numbers that multiply to result in that number. For example, 5 and 4 are a factor pair of 20.
- intersecting linesLines that cross.
- line
A set of points that are arranged in a straight way and extend infinitely in opposite directions.
- mixed numberA number expressed as a whole number and a fraction less than 1.
- multiple of a numberThe result of multiplying that number by a whole number. For example, 18 is a multiple of 3, because it is a result of multiplying 3 by 6.
- numerator
The top part of a fraction that tells how many of the equal parts are being described.
- obtuse angleAn angle that measures greater than 90 degrees.
- parallel linesLines that never intersect.
- perpendicular linesLines that intersect creating right angles.
- point
A location along a line or in space.
- prime numberA whole number that is greater than 1 and has exactly one factor pair: the number itself and 1.
- rayA line that ends at one point and goes on in the other direction.
- remainderThe number left over when we take away as many equal groups as we can from a number.
- right angleAn angle with a measurement of 90 degrees.
- rounding
A formal way to say which number a given number is closer to. For example, for 182, the number 180 is the closest multiple of ten and 200 is the closest multiple of a hundred. We can round 182 to 180 (if rounding to the nearest ten) or 200 (if rounding to the nearest hundred).
- segment or line segment
A part of a line with two endpoints.
- straight angleAn angle that measures 180 degrees.
- vertexThe point where the two rays meet.