Triangle with inscribed circle

In summary, the problem is to prove that in a triangle with an inscribed circle of radius greater than 1 and a point P inside the triangle, at least one of the distances from P to the vertices A, B, C is greater than 2. The solution involves using the formula for finding the minimum and considering the areas of the triangles formed by the point P and each of the vertices.
  • #1
klawesyn28
9
0
P is a point inside triangle ABC. In the triangle there is inscribed
circle which radius is greater than 1. Prove that PA>2, PB>2 or PC>2.


I don't know how to solve it. Could anybody help me?
 
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  • #2
Did you at least start the problem? If so then post what you have and we will help you from there.
 
  • #3
Yes I started with this problem and then I don't know how to prove that when PA<=2, PB<=2, PC<=2, the circumradius is smaller than 2. P is point inside the triangle.
 
  • #4
klawesyn28 said:
P is a point inside triangle ABC. In the triangle there is inscribed
circle which radius is greater than 1. Prove that PA>2, PB>2 or PC>2.
I don't know how to solve it. Could anybody help me?

This is one of those cases where the first step can be tough. You haven't said what kind of class this is for and so it's hard for us to figure out what kind of direction you're supposed to go in.

With that, here are some things you might think about.

(a) It would be really handy if you had a formula for the minimum that you could differentiate. It might be useful for you to know that:

[tex]min(A,B) = (|A+B| - |A-B|)/2[/tex]

(b) Do you think you could do something with the area formula for a triangle as compared to the area formula for the circle? Can you write an area formula that is defined around the point P? Perhaps the areas of the three triangles PAB, PBC, PCA?

Carl
 
  • #5
It's task from russian books with task from geometry. I don't see how your hints can help me.
 

Related to Triangle with inscribed circle

What is a triangle with inscribed circle?

A triangle with inscribed circle is a triangle where the circle is tangent to all three sides of the triangle. In other words, the circle is drawn inside the triangle and touches all three sides.

How is the circle inscribed in the triangle?

The circle is inscribed in the triangle when the center of the circle is located at the intersection of the angle bisectors of the triangle. This means that the center of the circle is equidistant from all three sides of the triangle.

What is the relationship between the triangle and the inscribed circle?

The inscribed circle is the largest possible circle that can be drawn inside a triangle. It is also known as the "incircle" of the triangle. The radius of the inscribed circle is also related to the sides of the triangle through the formula r = A/s, where r is the radius, A is the area of the triangle, and s is the semi-perimeter (half the sum of the side lengths).

What are the properties of a triangle with inscribed circle?

A triangle with inscribed circle has several unique properties. The most common ones include: all three angle bisectors are equal in length, the angle bisectors intersect at the center of the inscribed circle, the inradius (radius of the inscribed circle) is perpendicular to the sides of the triangle, and the sum of the distances from the center of the circle to each side is equal to the perimeter of the triangle.

What are some real-life applications of a triangle with inscribed circle?

Triangles with inscribed circles can be found in various real-life applications, such as in the design of circular tables, roundabouts, and wheels. They are also used in engineering and architecture for creating stable structures with triangular supports. In addition, the properties of the inscribed circle can help determine the location of the incenter (center of the inscribed circle) which is useful in navigation and surveying.

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