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

Vertically opposite angles are always

Prove that vertically opposite angles are equal.

A transversal intersects two parallel lines. Prove that the bisectors of any pair of corresponding angles so formed are parallel.

If a transversal intersects two lines such that the bisectors of a pair of corresponding angles are parallel,then prove that the two lines are parallel.

Prove that the bisector of the vertical angle of an isosceles triangle bisects the base at right angles.

If two lines intersect prove that the vertically opposite angles are equal

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 are acute angles, then the other pair of vertically opposite angles are __________.

Show that the bisector of vertical angle of an isosceles triangle bisects the base at right angles.

Prove that the bisectors of the angles of a linear pair are at right angle.

If two parallel lines are intersected by a transversal then prove that the bisectors of any pair of alternate interior angles are parallel.