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Let's do this question in the figure below B, C is equal to AC is equal to 80 angle C aid is equal

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to 40 degree angle.

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It was the video.

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Give it a try and then let's do it together.

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All right, we're back.

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I hope you've given it a try.

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It's given that B.S. is equal to Acey is equal to 80.

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So let me market like this now, because these two sides are equal.

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We know that isosceles triangle.

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If two sides are equal, the angles opposite the equal sides are also equal.

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Right.

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Therefore, these two angles are equal.

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Now, over here we have this side equal to this side.

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Therefore, these two and both are also equal.

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Now it's given that angle C, it is equal to forty degrees.

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Right now I can say that 40 plus X plus X is equal to 180 degrees as per the angles and property of

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a triangle.

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Therefore X is equal to 70 degree.

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Right, 180 minus 40 gives you one forty one forty by two.

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Gives you seventy degrees.

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All right.

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We have X as 70 degrees now x this angle over here is an external angle to triangle ABC.

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Right.

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Therefore, I can say that X is equal to Z plus and that's to Z.

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As for the exterior angle property of a triangle, therefore that is equal to 70 by two or X by two,

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which gives you thirty five degrees right now.

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Over here you can see that plus forty plus angle E it is equal to 180 degrees.

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Right.

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Why is that so.

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Because that's equal to this angle, which is a straight angle and the straight angle is equal to 180

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degrees.

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Therefore substituting the values for that we have thirty five plus forty plus.

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It is equal to 180 degree or angle, it is equal to one hundred and five degrees, which is your answer.