If two lines intersect; then the vertically opposite angles are equal.

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

Prove that vertically opposite angles are equal.

Vertically opposite angles are always

If two lines intersect each other, then the vertically opposite angles are equal.

Prove that if two lines intersect each other, then the vertically opposite angles are equal.

Theorem 6.1 : If two lines intersect each other, then 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 __________.

Read the following two statements which are taken as axiom: (i) If two lines intersect each other , then the vertically opposite angles are not equal. (ii) If a ray stands on a line , then the sum of two adjacent angles, so formed is equal to 180^(@) . Is this system of axioms consistent ? Justify your answer.