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In the given figure, the value of x is ______. 65°, 80°, 95°, 120°

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Question

In the given figure, the value of x is ______.

Options

  • 65°

  • 80°

  • 95°

  • 120°

MCQ
Fill in the Blanks
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Solution

In the given figure, the value of x is 120°.

Explanation:

In the given figure, we need to find the value of x

Here, according to the angle sum property of the triangle

In ΔABD

∠BAD + ∠DBA + ∠ADB = 180°

55° + ∠DBA + 25° = 180°

80 + ∠DBA = 180°

∠DBA = 180° - 80°

∠DBA  = 100°

∠DBA = 100°

Also, ABC is a straight line. So, using the property, “angles forming a linear pair are supplementary”, we get,

∠DBA + ∠DBC = 180°

100 + ∠DBC = 180°

∠DBC = 180° - 100°

∠DBC = 80°

Further, using the property, “exterior angle of a triangle is equal to the sum of two opposite interior angles”, we get

ext. ∠DOC + ∠OBC + ∠OCB

 x = 80°+ 40°

x = 120°

Thus, x = 120°

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Chapter 11: Triangle and its Angles - Exercise 11.4 [Page 28]

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R.D. Sharma Mathematics [English] Class 9
Chapter 11 Triangle and its Angles
Exercise 11.4 | Q 21 | Page 28

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