Angles: Parallel Lines Video 25 on Corbettmaths Question 1: Are the lines AB and CD parallel? Explain your answer Question 2: Find the missing angle Give reasons for your answer Question 3: Find x Question 4: Find x Question 5: Matilda is proving that the angles in a triangle add up to 180° She has started with this diagram Complete her
Warm-Up Exercises 3 1 Identify Pairs of Lines and Angles 3 2 Use Parallel Lines and Transversals 3 3 Prove Lines are Parallel 3 4 Find and Use Slopes of Lines 3 5 Write and Graph Equations of Lines 3 6 Prove Theorems About Perpendicular Lines CHAPTER 3: Parallel and Perpendicular Lines
The two parallel lines LM and NP are intersected by the line RS The arrows pointing to the same direction indicate that the lines are parallel (i) The corresponding angles are equal a = e b = f c = g d = h (ii) The alternate angles are equal c = e d = f (iii) The sum of two allied angles is 180o c + f = 180o d + e = 180o
Parallel Lines and Angle Pairs When two parallel lines are cut by a transversal, the following pairs of angles are congruent • corresponding angles • alternate interior angles • alternate exterior angles Also, consecutive interior angles are supplementary In the figure, m∠2 = 75 Find the measures of the remaining angles
relationships that occur with parallel lines and a transversal, and identify and prove lines parallel from given angle relationships • Lessons 3-3 and 3-4 Use slope to analyze a line and to write its equation • Lesson 3-6 Find the distance between a point and a line and between two parallel lines • parallel lines (p 126
Mathematics Grade 8 5 REMEMBER: Adjacent angles on a straight line are supplementary If they are adjacent angles on a straight line, then they add up to 180°
find unknown values in angles formed by a transversal and parallel lines Example If ml-I = 3x + 15, ml-2 = 4x — 5, 111/—3 = 5y, and nzL4 = 6z + 3, find x and y p Il q, so m Ll = m L 2 because they are corresponding angles r Il s, so mL2 = m because they are corresponding angles 3x + 15 = 3x + 15 — 3x 15 +5 20 Exercises x 5 5-3x mL2 15 =
3 1 Measuring Angles A protractor can be used to measure or draw angles Note The angle around a complete circle is is 360o The angle around a point on a straight line is 180o Worked Example 1 Measure the angle CAB in the triangle shown Solution Place a protractor on the triangle as shown The angle is measured as 47o Worked Example 2
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GÉOMÉTRIE DANS L ESPACE - Éditions Ellipses
EXERCICES Exercices DANS L’ESPACE Exercice 1 Représenter un cube en perspective cavalière, le nommer MAGRITEU puis réaliser son patron Faire de même pour un tétraèdre régulier MIRO Exercice 2 GAUDI est une pyramide régulière de sommet G: sa base est un carré de centre O, ses faces latérales sont des triangles équilatéraux de côté 4cm 1 Calculer la hauteur de cette pyramide puis en donner
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1 ANGLES ET TRIANGLES SEMBLABLES
Méthode : Appliquer la propriété de parallélisme sur les angles alternes-internes Vidéo https://youtu be/v7XmtQhOP9I Sur la figure, les droites (DE) et (CF) sont- elles parallèles ? L’angle ABG est plat donc : ABC = 180 – 102 = 78° Les angles ABC et BAE sont alternes-internes et égaux Si deux angles alternes-internes sont égaux
rière à la sortie de l'X et en paral- lèle une vus sous les angles : tés requises : goût des contacts, dynamisme, réa- lisme Evolution des responsabilités et de la rému- Des exercices en fin de chapitre, de prouver, sans représentation géométrique, tous les théorèmes d'Euclide IJlObiles (SFR, opérator), interna-
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