In Fig.19, name each linear pair and each pair of vertically opposite angles:

In Fig. 15, write down: (i) each linear pair (ii) each pair of vertically opposite angles.

In Fig (5.18) identify:(i) Five pairs of adjacent angles. (ii) Three linear pairs.(iii) Two pairs of vertically opposite angles

Fill in the blanks:(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 areacute angles, then the other pair of vertically opposite angles are __________.

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

In Fig.14, name all the pairs of adjacent angles.

Indicate which pairs of angles are:(i) Vertically opposite angles. (ii) Linear pairs.

Prove that the bisectors of a pair of vertically opposite angles are in the same straight line.

In the adjoining figure, identify(i) the pairs of corresponding angles.(ii) the pairs of alternate interior angles.(iii) the pairs of interior angles on the sameside of the transversal.(iv) the vertically opposite angles.

If two straight lines intersect each other, prove that the ray opposite to the bisector of one of the angles thus formed bisects the vertically opposite angle.

In Fig.18 A , B , C are collinear point and /_D B A=\ /_E B Adot (i) Name two linear pairs (ii) Name two pairs of supplementary angles.