Two straight line are parallels if and only if their slopes are ____.

Write the negatin of each of the statement : Two lines are parallel if and only if they have the same slope.

Write the negatin of each of the statement : Two lines are parallel if and only if they have the same slope.

Given below are pairs of statements. Combine them using ‘if and only if' : p: If two lines are parallel, then their slopes are equal. q: If the slopes of two lines are equal, then they are parallel.

Rewrite each of the following statements in the form 'p if and only if q'. Give below are pairs of statements. Combine them using 'if and only if' : p : If two lines are parallel, then their slopes are equal. q : If the slopes of two lines are equal, then they are parallel.

Two straight lines are cut by a transversal. If the bisectors of a pair of co-interior angles are perpendicular to each other , prove the two straight lines are parallel to each other.

Two straight lines are cut by a transversal. If the bisectors of a pair of co-interior angles are perpendicular to each other , prove the two straight lines are parallel to each other.

If a straight line divdes two sides of a triangle proportionally, then the straight line a parallel to third sides, (Converse of Thales theorem). Prove.

There are 20 straight lines in a plane so that no two lines are parallel and no three lines are concurrent. Determine the number of points of intersection.