# Ex.5.2 Q1 Lines and Angles - NCERT Maths Class 7

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## Question

State the property that is used in each of the following statements?

(i) If \(a || b,\) then \(\angle1 = \angle5.\)

(ii) If \(\angle4 = \angle6,\) then \(a || b.\)

(iii) If \(\angle4 + \angle5 = 180^\circ,\) then \(a || b.\)

## Text Solution

**Steps:**

(i) If two parallel lines are intersected by a transversal, then each pair of corresponding angles are equal .

(ii) When a transversal intersects two parallel lines such that if pair of alternate interior angles are equal then the lines are parallel.

(iii) When a transversal intersects two parallel line such that pair of interior angles on the same side of transversal are supplementary, then the lines are parallel.