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Students in this video, let's discuss an important theorem which is very useful in solving a lot of

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questions called the second tangent theorem.

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Over here I have a circle with center O and a B is a second.

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OK, so it's interesting, the circle at two points and B and L is a tangent at point B now as per the

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second tangent theorem, angle A, B, B, that is this angle over here will be equal to the angle SUB-STANDARD

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baby that's angle HCB.

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Or here to ask for this theorem angle B is equal to angle HCB.

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All right, now over here, you can note that this angle over here is the angle between the second and

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the tangent, you have the second over here and the tangent over here.

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But this is the angle between the second and the tangent.

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Now, let's try to understand why this is true.

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Let's join in with all and all will be all right.

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Now, these two angles will be equal because or and or B are equal.

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Right.

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So it is an isosceles triangle now as angle HCB.

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That's this angle over here is theta.

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Therefore we can find that angle A or B will be equal to two Tetum.

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Right.

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Because Angle AOB is the measure of archabbey and angle.

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ACB is an angle sub-standard by the same arc and we have seen that the angle SUB-STANDARD will be half

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the measure.

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Right, or the measure will be twice the SUB-STANDARD angle.

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So AOB is equal to Tetum already.

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Now let's observe isosceles triangle.

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It will be we have angle y angle.

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Right and this angle over here will be to teeter right.

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Therefore we can find that angle y will be 180 minus two feet by two.

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That's equal to 90 minus to.

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All right.

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Now angle all BP will be equal to 90 degree.

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Right, because it is a tangent.

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OK, so now let's find angle B B, that's what we are trying to find, right?

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This is data and we are trying to prove that angle.

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Pibor also is equal to data.

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All right.

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So angle B B will be equal to 90.

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That's this angle over here, minus Y, right.

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If you subtract from this angle y, you are left with only this much and that is angle PVA.

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That's 90 minus Y and we know Y is equal to 90 minus theta will be substituted over here.

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So we get ninety minus 90 plus theta which is equal to Tweetup.

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So angle B B, A is equal to Peter.