Step: 1

If the sum of two angles is 180°, then, the angles are called supplementary angles.

Step: 2

From the figure, ∠ 1 and ∠ 2, ∠ 2 and ∠ 3, ∠ 3 and ∠ 4, ∠ 4 and ∠ 1 form supplementary angles.

Step: 3

[∠ 1 and ∠ 2 form supplementary angles.]

Step: 4

125° + ∠ 2 = 180°

[Substitute ∠ 1 = 125°.]

Step: 5

[Subtract 125° on both the sides.]

Step: 6

[∠ 2 and ∠ 3 form supplementary angles.]

Step: 7

55° + ∠ 3 = 180°

[Substitute ∠ 2 = 55°]

Step: 8

[Subtract 55° on both the sides.]

Step: 9

[∠ 3 and ∠ 4 form supplementary angles.]

Step: 10

125° + ∠ 4 = 180°

[Substitute ∠ 3 = 125°.]

Step: 11

[Subtract 125° on both the sides.]

Correct Answer is : 55°, 125° and 55°

Step: 1

Given, ∠ AOC = 30°.

Step: 2

Sum of ∠ AOC and ∠ COB is 180°.

[AB is a straight line.]

Step: 3

Hence, ∠ AOC + ∠ COB = 180°.

Step: 4

30° + ∠ COB = 180°.

[Substitute ∠ AOC = 30°.]

Step: 5

[Subtract 30° on both sides.]

Correct Answer is : 150°

Step: 1

When two lines intersect, two pairs of congruent opposite angles are formed. angles in each such pair are called vertical angles.

Step: 2

Amongst the choices, ∠2 and ∠4 are the pair of vertical angles.

Correct Answer is : ∠ 2 and ∠ 4

Step: 1

Given, ∠ AOC = 25^{o}.

Step: 2

Sum of ∠ AOC and ∠ COB is 180^{o}.

[Since, AB is a straight line.]

Step: 3

Hence, ∠ AOC + ∠ COB = 180^{o}.

Step: 4

25^{o} + ∠ COB = 180^{o}.

[Substitute ∠ AOC = 25^{o}.]

Step: 5

[Subtract 25^{o} on both sides.]

Correct Answer is : 155^{o}

Step: 1

When two adjacent angles form 180° they are called **supplementary angles**.

Step: 2

Step: 3

[Sum of supplementary angles = 180°]

Step: 4

Step: 5

Step: 6

Therefore, the supplementary angle of 130° is 50°.

Correct Answer is : 50°

Step: 1

If a transversal intersects two parallel lines, the interior angles are supplementary.

Step: 2

In the figure, l and q are interior angles. Hence, they are supplementary.

Step: 3

So, l and q are supplementary angles.

Correct Answer is : l and q

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