The measures of vertical angles are equal.

∠ 1 = ∠3

∠ 2 = ∠4

In fact these angles are congruent.

In other word, we can say that two angles formed by two intersecting lines having no common arm are called

Note : From the above figure, we can say that ∠1 and ∠2 form a linear pair. Also , ∠2 and ∠3; ∠3 and ∠4 ; ∠4 and ∠1.

1) Find the value of ‘y’.

Since ∠COD and ∠ EOF are vertical angles.

∴ ∠ COD = ∠ EOF

⇒ ∠COD = 5y

Now, OA and OB are opposite rays.

∴ ∠AOD + ∠DOC + ∠COB = 180

⇒ 2y + 5y + 5y = 180

⇒ 12y = 180

⇒ y = 180/12

⇒ y = 15.

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1) If the two vertical angles are 5x and 120

2)If two lines intersect each other, then vertical angles are _______.

3)

m∠1 = 35

4) The two lines l and m intersect each other at O, write the names of vertical angles.

5) Two lines are perpendicular to each other. Write the measure of all four angles formed by these two lines.

• Point

• Lines

• Angles

• Lines and Angles

• Complementary angles

• Supplementary angles

• Vertically Opposite Angles

• Linear Pair Angles

• Adjacent Angles

• Parallel Lines

• Solved Problems on Intersecting Lines

• Solved Problems on Parallel Lines