LINES AND ANGLES 11. In the following figure, is ∠1 adjacent to ∠2? Give reasons. 12. Find the values of the angles x, y, and z in each of the following: (i) If two angles are complementary, then the sum of their measures is _______. (ii) If two angles are supplementary, then the sum of their measures is ______. (iii) Two angles forming a linear pair are _______________. (iv) If two adjacent angles are supplementary, they form a ___________. (v) If two lines intersect at a point, then the vertically opposite angles are always _____________. (vi) If two lines intersect at a point, and if one pair of vertically opposite angles are acute angles, then the other pair of vertically opposite angles are __________. 14. In the adjoining figure, name the following pairs of angles. (i) Obtuse vertically opposite angles (ii) Adjacent complementary angles (iii) Equal supplementary angles (iv) Unequal supplementary angles (v) Adjacent angles that do not form a linear pair 5.3 PAIRS OF LINES 5.3.1 Intersecting Lines LINES AND ANGLES In the Fig 5.22, p is a transversal to the lines l and m. Interior angles ∠3, ∠4, ∠5, ∠6 Exterior angles ∠1, ∠2, ∠7, ∠8 Pairs of Corresponding angles ∠1 and ∠5, ∠2 and ∠6, ∠3 and ∠7, ∠4 and ∠8 Pairs ofAlternate interior angles ∠3 and ∠6, ∠4 and ∠5 Pairs ofAlternate exterior angles ∠1 and ∠8, ∠2 and ∠7 Pairs of interior angles on the same side of the transversal ∠3 and ∠5, ∠4 and ∠6 Note: Corresponding angles (like ∠1 and ∠5 in Fig 5.25) include(i) different vertices (ii) are on the same side of the transversal and MATHEMATICS (iii) are in ‘corresponding’positions (above or below, left or right) relative to the two lines. Fig 5.25 Alternate interior angles (like ∠3 and ∠6 in Fig 5.26) (i) have different vertices (ii) are on opposite sides of the transversal and (iii) lie ‘between’ the two lines. Fig 5.26 5.3.4 Transversal of Parallel Lines Do you remember what parallel lines are? They are lines on a plane that do not meet anywhere. Can you identify parallel lines in the following figures? (Fig 5.27)

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