Question

Emergency emergency emergency ​

Answer 1

Answer:

when they have same perpendicular difference at every point

and they line passing through them

make angle who sums 180'

In simple words

when the sum of co-interior angle is 180'

Answer 2

Answer:

Parallel lines have the same slope and will never intersect.

(i) Condition for the lines to be parallel in terms of their slopes.

Let m1 and m2 be the slopes of two lines.

If the two lines are parallel, then their slopes will be equal.

That is,

m1 = m2

(ii) Condition for the lines to be parallel in terms of their general form of equations.

Let us consider the general form of equation of a straight line.

ax + by + c = 0

If the two lines are parallel, then their general forms of equations will differ only in the constant term and they will have the same coefficients of x and y.

That is,

ax + by + c1 = 0

ax + by + c2 = 0

(iii) Condition for the lines to be parallel in terms of their slope-intercept form of equations.

Let us consider the slope intercept form of equation of a straight line.

y = mx + b

If the two lines are parallel, then their slope-intercept form equations will will differ only in the "y"- intercept.

That is,

y = mx + b1

y = mx + b2

(iv) Condition for the lines to be parallel in terms of angle of inclination.

Let l1 and l2 be two lines.

If the two lines are parallel, the angle between them and the positive side of x-axis will be equal.