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Mathematics: Geometry Grade 5 Types of Angles Picture Name of Angle Description Acute Angle I am the smallest type of angle and I am very CUTE. I am always less than 90º. Right Angle I am perfectly straight and always RIGHT. I am exactly 90º. Obtuse Angle I am a lot more relaxed than the Right Angle, and therefore OBviously more than 90º, but less than 180º. Straight line I like to walk on the STRAIGHT and narrow line, I never go anywhere but 180º. Reflex Angle I am so FLEXible that I can bend all the way past 180º. Revolution I don’t like to be like the rest, I want a REVOLUTION and we can all dance in a circle. I am exactly 360º. Charlie says: “Always start on the horizontal line, then walk toward the angled line.” 45º 129º 180º 135º 360º Mathematics: Geometry Grade 5 Identifying Angles Can you identify the indicated angles in these pictures? Give the name and description of each angle. 1 _______________ ________________ 2 _______________ ________________ ________________ 3 ________________ ________________ 4 1 _____________ ________________ _____________ ________________ ________________ 2 ________________ See if you can find all these angles in each of the pictures below: Draw the Obtuse angles in red, the Right angles in blue, the Acute angles in black and the Reflex angles in Green. Make sure that you find ALL the angles in each picture! 2 Mathematics: Geometry Grade 5 Measuring and Drawing Angles When measuring angles, we use a protractor. A protractor has an inner scale and an outer scale. The way in which the angle faces, will indicate to you if you should use the inner or outer scale to measure or draw the angle. Acute angle, facing left, will be measured or drawn using the outer scale (0º— 90º) Acute angle, facing right, will be measured or drawn using the inner scale (0º— 90º) Obtuse angles, facing right, will be measured with the inner scale (90º—180º) Obtuse angles, facing left, will be measured with the outer scale (90º—180º) A STEPS to follow for measuring angles: Step 1: Make sure which angle you should be measuring. ABC, means you have to measure angle B. Step 2: Extend any lines with your ruler to ensure that you can see the line all the way past your protractor. Step 3: Make a dot where the two lines meet, big enough for you to see through the protractor. This will help you put the protractor exactly in the middle. Step 4: Decide if you will measure with the inner or outer scale, using the explanation above. B C Step 5: Make sure your protractor is exactly straight on the bottom line and that your dot is exactly on the perpendicular line facing towards 90º. Step 6: Measure the angle—in this example, the angle measures 55º. STEPS to follow for drawing perfect angles: Step 1: Always start with a dot where you would like to draw your angle, then draw a straight horizontal line from where you will begin. Step 2: Measure the angle using your protractor. Remember to follow the instructions carefully. Is it facing right or left? Will it be an Acute angle or an Obtuse angle? The answer to these questions will tell you if you will be using the inner or outer scale. Step 3: Make a visible mark at exactly the correct degrees. Remember to make sure that your protractor does not move while you are measuring. Step 4: Connect your dot with that mark, using a ruler. Step 5: Draw a semi-circle or a square (90º) to indicate the angle you have measured and write in the degrees of that angle. 3 Mathematics: Geometry Grade 5 Measuring and Drawing Angles Measure the following angles, using your protractor: HINT: Turn the page, until the angle you have to measure is horizontal. C X Y D E Z Type of angle: Type of angle: Size of Size of CDE: XYZ: R G E S T F Type of angle: Type of angle: Size of Size of EFG: RST: K 17 H L 70 I 93 M G Type of angle: Type of angle: Size of Size of GHI: 4 KLM: Mathematics: Geometry Grade 5 Measuring and Drawing Angles Draw the following angles in the space provided: ABC, 76º, left facing DEF, 162º, left facing XYZ, 29º, right facing MNO, 83º, right facing JKL, 146º, right facing GHI, 101º, left facing 5 Mathematics: Geometry Grade 5 Identifying Angles—Memo Can you identify the indicated angles in these pictures? Give the name and description of each angle. 1 Obtuse angle, bigger 1. Right angle, 90º 2 than 90º, smaller than 2. Obtuse angle, > 90º,<180º 180º 3 3. Reflex angle, > 180º 4. Acute angle, < 90º 4 1 Obtuse angle, 1. Reflex angle, > 180º > 90º, < 180º 2. Acute angle, < 90º 2 See if you can find all these angles in each of the pictures below: Draw the Obtuse angles in red, the Right angles in blue, the Acute angles in black and the Reflex angles in Purple. Make sure that you find ALL the angles in each picture! Remember that angles forms only where STRAIGHT lines meet. 6 Mathematics: Geometry Grade 5 Measuring and Drawing Angles—Memo Measure the following angles, using your protractor: HINT: Turn the page, until the angle you have to measure is horizontal 43.5 C X Y E 49.5 84 D 92.9 43.6 Z46.5 Type of angle: Obtuse Type of angle: Acute Size of Size of 43 .5 CDE: 92º R 46 .5 G XYZ: 84º 15 .8 E 14 8 90 S 1T 6.2 F Type of angle: Right Type of angle: Obtuse Size of Size of EFG: 90º 2K6 .2 17 H 93 M 25 .8 L 70 I RST: 148º 12 8 G Type of angle: Acute Type of angle: Obtuse Size of Size of GHI: 17º 7 KLM: 128º Mathematics: Geometry Grade 5 Measuring and Drawing Angles—Memo Draw the following angles in the space provided: ABC, 76º, left facing DEF, 162º, left facing A 68.8 F 76º 35.2 DA B 76 E C XYZ, 29º, right facing MNO, 83º, right facing M X Y 29º Z N O JKL, 146º, right facing GHI, 101º, left facing I J L 101º K G 8 H