# Three lines AB, CD and EF intersect each other at O. If ∠AOE = 30° and ∠DOB = 40° (Fig. 5.51), find ∠COF.

**Solution:**

Given, three lines AB, CD and EF intersect each other at O.

Also, ∠AOE = 30° and ∠DOB = 40°

We have to find the measure of ∠COF.

We know that the sum of all angles lying on a __straight line__ is equal to 180 degrees.

∠AOE + ∠EOD + ∠BOD = 180°

From the figure,

30° + ∠EOD + 40° = 180°

70° + ∠EOD = 180°

∠EOD = 180° - 70°

∠EOD = 110°

We have to find the angles x, y and z.

__Vertically opposite angles__ are angles that are opposite one another at a specific vertex and are created by two straight intersecting lines.

Vertically opposite angles are equal to each other.

From the figure,

∠EOD = ∠COF

Therefore, ∠COF = 110°

**✦ Try This: **In the figure given above, l∥m. Find the values of x.

**☛ Also Check: **NCERT Solutions for Class 7 Maths Chapter 5

**NCERT Exemplar Class 7 Maths Chapter 5 Problem 94**

## Three lines AB, CD and EF intersect each other at O. If ∠AOE = 30° and ∠DOB = 40° (Fig. 5.51), find ∠COF.

**Summary:**

Three lines AB, CD and EF intersect each other at O. If ∠AOE = 30° and ∠DOB = 40° (Fig. 5.51), then ∠COF is 110°.

**☛ Related Questions:**

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- Two angles are making a linear pair. If one of them is one-third of the other, find the angles

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