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Prove: If two circles are tangent internally at point P and chord PA

of the larger circle intersects the smaller circle at B, then the measure of arc PA is equal to the measure of arc PB.

User Matt Stern
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1 Answer

6 votes

Answer:

Proved

Explanation:

Given:

Two circles are tangent internally at point P and chord PA of the larger circle intersects the smaller circle at B.

Prove: measure of arc PA is equal to measure of arc PB

To better understand this, the diagrams have been attached.

From triangle PQB:

Line PQ and line QB are radius of the smaller circle.

Reason: their line are straight lines drawn from the center of the circle to the circumference of the circle

Line PQ = Line QB

That is, side PQ = side QB

Since side PQ = side QB, it is an isosceles triangle.

Therefore < QPB = <PBQ

From triangle PRA

Line PR = line RA

Side PR = side RA

From triangle PRA:

Line PR and line RA are radius of the bigger circle.

Reason: their line are straight lines drawn from the center of the circle to the circumference of the circle

Line PR = Line RA

Since side PR = side RA, it is an isosceles triangle.

Therefore < RPA = <PAR

Using similar triangles theorem:

Triangle PQB = Triangle PRA

<PBQ = <PAR

Since they are equal, the measure of the arc (angle subtended by the arc) are equal.

Therefore measure of arc PA = measure of arc PB

Prove: If two circles are tangent internally at point P and chord PA of the larger-example-1
Prove: If two circles are tangent internally at point P and chord PA of the larger-example-2
User Jeaneen
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4.1k points