36. Show that each angle of equilateral triangle is 60°
Answers
Show that each angle of equilateral triangle is 60°
- Let ABC be an equilateral triangle.
✏ In an equilateral triangle, all sides are equal.
✏ ∴ AB = BC = AC
✏ Each angle of equilateral triangle is 60°
✏ i.e ∠A + ∠B + ∠C = 60°
⇒ AB = AC
⇒ ∠B = ∠C ──────────── ( i )
( ∵ Angles opposite to opposite sides are equal )
Also,
⇒ AC = AB
⇒ ∠A = ∠B ──────────── ( ii )
( ∵ Angles opposite to opposite sides are equal )
From ( i ) and ( ii ), we get:
⇒ ∠A = ∠B = ∠C ──────────── ( iii )
⇒ ∠A + ∠B + ∠C = 180° ( Angle sum property of a ▲ )
⇒ ∠A + ∠A + ∠A = 180°
⇒ 3∠A = 180°
⇒ ∠A = 180°/3
⇒ ∠A = 60°
∴ ∠A + ∠B + ∠C = 60°
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Answer:
By angle sum property we know that the sum of all the angles of a triangle is 180
We know that all the sides of a triangle are equal.
i.e all the angles of an equilateral triangle are equal.
Let each angle be x.
x+x+x=180
60o
3x = 180
⇒x = 60
Hence the answer.
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