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In this video, let's discuss the anger, some property of a triangle.

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Let's take an example of a triangle.

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We have Triangle ABC over here.

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As for the angles and property, angle it plus angle B plus Anglesey is equal to 180 degrees.

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And this is true for any triangle.

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Let's see why this is so.

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Let's produce B.S. and market point B over here.

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Now let's mark the internal angles as well as the exterior angle formed over here.

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But we have angle one, two and three, which are interior angles of this triangle.

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And angle four is the exterior angle formed at Vertex Seat already by the exterior angle property.

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We know that angle four is equal to angle one plus angle two.

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Right, because the exterior angle is equal to the sum of the interior opposite angles.

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All right.

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Now, angle three plus angle four is equal to 180 degree because these two angles form a linear pair.

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Right.

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All right.

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Now let's substitute the value of angle for which we have over here into this equation.

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Therefore, we get angle three plus angle two plus angle one.

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That is the sum of the interior angles is equal to 180 degrees.

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And remember, this is true for any triangle.