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The Vertical Angle of an Isosceles Triangle is 100°. Find Its Base Angles.

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प्रश्न

The vertical angle of an isosceles triangle is 100°. Find its base angles. 

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उत्तर

Consider an isosceles ΔABC such that AB= AC 
Given that vertical angle A is 100°.  Given to find the base angles
SinceΔABC is isosceles 

∠B = ∠C                   [Angles opposite to equal angle are equal] 

And also , 

Sum of the interior angle of a triangle = 180° 

⇒∠Aa+∠B+∠C=180° 

⇒100°+∠B+∠B=180°  

⇒2∠B=180°-100° ⇒2∠B=80°

⇒∠B=40 °

⇒∠B=∠C=40°    

 

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अध्याय 12: Congruent Triangles - Exercise 12.1 [पृष्ठ १५]

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आर.डी. शर्मा Mathematics [English] Class 9
अध्याय 12 Congruent Triangles
Exercise 12.1 | Q 6 | पृष्ठ १५

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