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