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Question
If each of the two equal angles of an isosceles triangle is 68°, find the third angle.
Solution
Let Δ ABC is an isosceles triangle
∴ In Δ ABC, AB = AC
and ∠B = ∠C = 68°
But ∠A + ∠B + ∠C = 108° ...(Sum of angles of a triangle)
⇒ ∠A + 68° + 68° = 180°
⇒ ∠A + 136° = 180°
⇒ ∠A = 180° - 136°
∴ ∠A = 44°
Hence third angle = 44°
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