* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Lesson 10.2
Survey
Document related concepts
Dessin d'enfant wikipedia , lookup
Penrose tiling wikipedia , lookup
Technical drawing wikipedia , lookup
Multilateration wikipedia , lookup
Golden ratio wikipedia , lookup
Euler angles wikipedia , lookup
Apollonian network wikipedia , lookup
Rational trigonometry wikipedia , lookup
Trigonometric functions wikipedia , lookup
Reuleaux triangle wikipedia , lookup
History of trigonometry wikipedia , lookup
Euclidean geometry wikipedia , lookup
Incircle and excircles of a triangle wikipedia , lookup
Transcript
Lesson 10.2 Name Classify Triangles by Angles Geometry— 4.G.A.2 Also 4.G.A.1 MATHEMATICAL PRACTICES MP3, MP4, MP6, MP7 Essential Question How can you classify triangles by the size of their angles? Unlock Unlock the the Problem Problem A triangle is a polygon with three sides and three angles. You can name a triangle by the vertices of its angles. Triangle Possible Names A B C nABC nACB nBCA nBAC nCAB nCBA When you see “nABC,” say “triangle ABC.” An angle of a triangle can be right, acute, or obtuse. Activity 1 Identify right, acute, and obtuse angles in triangles. Materials ■ color pencils Use the Triangle Color Guide to color the triangles below. Triangle Color Guide © Houghton Mifflin Harcourt Publishing Company Math Talk Try This! a. Name the triangle with one right angle. _ c. Name the triangle with three acute angles. _ B one right angle BLUE one obtuse angle ORANGE three acute angles MATHEMATICAL PRACTICES 7 Look for Structure Can a triangle have more than one obtuse angle? Explain. P A b. Name the triangle with one obtuse angle. _ RED C R Z Q X Chapter 10 Y 555 An acute triangle is a triangle with three acute angles. An obtuse triangle is a triangle with one obtuse angle. Acute Triangle A right triangle is a triangle with one right angle. Obtuse Triangle Right Triangle Activity 2 Use a Venn diagram to classify triangles. Write the names of the triangles in the Venn diagram. M W S G D B R T V P Q L X A N B C I F H D R E C Triangles Acute Triangles Obtuse Triangles Math Talk 556 MATHEMATICAL PRACTICES 4 Interpret a Result Explain why the three circles in this Venn diagram do not overlap. © Houghton Mifflin Harcourt Publishing Company Right Triangles Name Share hhow Share and and Show Sh MATH M BOARD B 1. Name the triangle. Tell whether each angle is acute, H right, or obtuse. A name for the triangle is __ . F /F is __ . G /G is __ . /H is __ . Classify each triangle. Write acute, right, or obtuse. 2. 3. ___ 4. ___ ___ On On Your Your Own Own Classify each triangle. Write acute, right, or obtuse. 5. 6. ___ SMARTER ___ ___ Cross out the figure that does not belong. Explain. © Houghton Mifflin Harcourt Publishing Company 8. 7. Chapter 10 • Lesson 2 557 MATHEMATICAL PRACTICES .0%&-t3&"40/tM",&4&/4& OqnakdlRnkuhmf¤@ookhb`shnmr OqnakdlRnkuhmf¤@ookhb`shnmr Use the Venn diagram for 9–10. SMARTER Which triangles do NOT have an obtuse angle? Explain. Acute Triangles nDEF nSPN 10. 11. 12. MATHEMATICAL PRACTICE 6 How many triangles have at least two acute angles? Explain. DEEPER Use the square shown at the right. Draw a line segment from point M to point P. Name and classify the triangles formed by the line segment. SMARTER nABC nGHP nJKL nVXE nWZR N P M Q Write the letter of the triangle under its correct classification. B C A E D Acute Triangle 558 Obtuse Triangles Right Triangles Obtuse Triangle F Right Triangle © Houghton Mifflin Harcourt Publishing Company 9. Triangles Practice and Homework Name Lesson 10.2 Classify Triangles by Angles COMMON CORE STANDARD—4.G.A.2 Draw and identify lines and angles and classify shapes by properties of their lines and angles. Classify each triangle. Write acute, right, or obtuse. 1. A Think: Angles A and C are both acute. Angle B is obtuse. B C obtuse F 2. D J 3. G 4. L M H E N Problem Problem Solving Solving 5. Use figure ABCD below. Draw a line segment from point B to point D. Name and classify the triangles formed. © Houghton Mifflin Harcourt Publishing Company A D 6. Math Draw and label an example of a right triangle, an acute triangle, and an obtuse triangle. WRITE B C Chapter 10 559 TEST PREP Lesson Check (4.G.A.2) 1. Stephen drew this triangle. How many obtuse angles does the triangle have? 2. Joan was asked to draw a right triangle. How many right angles are in a right triangle? Spiral Review (4.OA.B.4, 4.NBT.B.5, 4.NF.C.5, 4.G.A.1) 3. Oliver drew the figure below to show light traveling from the Sun to Earth. Name the figure he drew. 8 1 ___ 4. Armon added __ 10 and 100 . What is the sum of these fractions? S E out loud by 8s. What are the first three numbers both Sam and Jorge said? 6. A basketball team averaged 105 points per game. How many points did the team score in 6 games? FOR MORE PRACTICE GO TO THE 560 Personal Math Trainer © Houghton Mifflin Harcourt Publishing Company 5. Sam counted out loud by 6s. Jorge counted