Perpendicular Bisector of a triangle

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SUMMARY

The discussion centers on the geometric concept of the perpendicular bisector of a triangle, specifically how it intersects the sides of triangle ABC. Participants clarify that the perpendicular bisector of segment BC intersects line segment BA at point P and extends to intersect the extended line segment CA at point Q. The confusion arises from the placement of point P in the diagram, which should be accurately represented to reflect the correct geometric relationships. The calculations involving triangle PQC and the tangent function are also discussed, highlighting discrepancies with textbook answers.

PREREQUISITES
  • Understanding of triangle geometry and properties of perpendicular bisectors.
  • Familiarity with trigonometric functions, specifically tangent.
  • Ability to interpret and construct geometric diagrams accurately.
  • Knowledge of angle measurement in degrees and minutes.
NEXT STEPS
  • Study the properties of perpendicular bisectors in triangles.
  • Learn how to apply the tangent function in right triangles.
  • Practice constructing accurate geometric diagrams based on given conditions.
  • Review angle conversion between degrees and minutes for precise calculations.
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Students studying geometry, educators teaching triangle properties, and anyone seeking to improve their understanding of geometric constructions and trigonometric applications.

nmnna
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Homework Statement
##ABC## is a triangle such that ##\angle ABC = 37^{\circ}15'##, ##\angle ACB = 59^{\circ}40'##, ##BC = 8## cm; the perpendicular bisector of ##BC## cuts ##BA##, ##CA## produced at ##P, \ Q##. Find the length of ##PQ##.
Relevant Equations
##\tan(\alpha) = \frac{opposite \ side}{adjacent \ side}##
Here is my attempt to draw a diagram for this problem:
1617268604102.png

I'm confused about the "the perpendicular bisector of ##BC## cuts ##BA##, ##CA## produced at ##P, \ Q##" part of the problem.
How does perpendicular bisector of ##BC## cut the side ##CA##?
 
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It cuts CA produced. Extend the line CA until it meets the bisector. That point is Q (not where you have put it).
 
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mjc123 said:
It cuts CA produced. Extend the line CA until it meets the bisector. That point is Q (not where you have put it).
Thank you
 
mjc123 said:
It cuts CA produced. Extend the line CA until it meets the bisector. That point is Q (not where you have put it).
1617290558617.png

I changed my diagram.
Now I have the right triangle ##\triangle PQC##, where ##CP = 4##cm (since ##PQ## is a perpendicular bisector), ##\angle QCP = 59^{\circ}40'##, so I can find ##PQ## using the relation $$\tan\angle QCP = \frac{PQ}{CP}$$
I got ##\approx 6.818## which is not the answer given in my textbook. Where did I go wrong?
 
Last edited:
nmnna said:
View attachment 280723
I changed my diagram.
Now I have the right triangle ##\triangle PQC##, where ##CP = 4##cm (since ##PQ## is a perpendicular bisector), ##\angle QCP = 59^{\circ}40'##, so I can find ##PQ## using the relation $$\tan\angle QCP = \frac{PQ}{CP}$$
I got ##\approx 6.818## which is not the answer given in my textbook. Where did I go wrong?
The description seems confusing to me as well.
Could it be that point P should be located where the perpendicular bisector of BC cuts BA?
What is the answer given in your textbook?
If it is close to 3.75 cm, then your last diagram is not correct regarding location of P.
 
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P is the point you have called L. The original statement, which is perhaps not as clear as it might be, means "the perpendicular bisector of BC cuts BA at P and cuts CA produced at Q."
 
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mjc123 said:
P is the point you have called L. The original statement, which is perhaps not as clear as it might be, means "the perpendicular bisector of BC cuts BA at P and cuts CA produced at Q."
Thank you for your help.
 

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