Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [triangles]

For questions about properties and applications of triangles.

A triangle is a polygon with three sides. It is an important geometric figure, because any polygon can be subdivided into triangles.

Triangles can be classified by the number of sides they have that have equal length

  • All three sides of an equilateral triangle have equal length.
  • An isosceles triangle has at least two sides of equal length.
  • A scalene triangle is a triangle that is not isosceles, that is, it has no sides with equal length.

A triangle may also be classified by describing its angles. A triangle is said to be a right triangle if it contains a right angle, and obtuse triangle if it contains an obtuse angle, or an acute triangle if all three of its angles are acute.

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Smallest turning angle

I know it's probably been answered, but my google-fu is failing me today... I have two 2D points; A and B A has a known Heading. The X and Y coordinates are always positive, if that helps at all. What I would like to do is figure out the angle that…
Trent
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Using Pascal's Triangle for Binomial Expansion.

I'm trying to answer a question using Pascal's triangle to expand binomial functions, and I know how to do it for cases such as (x+1) which is quite simple, but I'm having troubles understanding and looking for a pattern when the question changes to…
Math student
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isosceles and tight triangle

Hi, I was wondering if there is a way to find x with only knowing the length of isosceles triangle and no other piece of information.
Ali Baker
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Locus Similar Triangle

ABC is a triangle and XY is variable straight line parallel to AC meeting BC and BA in X, Y respectively. If AX and CY meet at P find the locus of P.
Apoorv Jain
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Prove inequality in a triangle

Prove that In a triangle having sides $a, b, c$ $$a^2(b+c-a)+b^2(a+c-b)+c^2(a+b-c)\le 3abc.$$ I tried using the basic two side sum greater than third property but got nothing hope you guys help me.
Apoorv Jain
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Length of a segment on right triangles that share same hypotenuse

I have two right triangles that share the same hypotenuse. Can the length of Xb be found using just the other lengths shown (X, L, Y)? I have only been able to find it by using a combination of the asine, atangent, and tangent of the resulting…
user154739
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Finding the ratio of a dissected isosceles?

I have trouble trying to find relationship between sub-triangles.
user153250
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How to determine the range of a angle measure?

In $\Delta$ $KLM$, $KL=20$ $LM=13$ m$\angle K$$=40$. What is the range for angle $M$'s measure? Something like between $90^{\circ}$ and $180^{\circ}$.
most venerable sir
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what is the measure of angle ECD from this following triangle problem?

In triangle ABC, AB is larger than BC. Then, we choose point E outside the triangle such that BE=BC. We extend line AB to D, such that BD=BC. BF is angle bisector of angle ABC. If DC is parallel to BF, what is the measure of angle ECD?
akusaja
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Calculate an angle between time 00:00 and a mouse cursor position

I have to build a timepicker where user clicks on a clock like circle and it gives a time. Once I have cursor position I think that all I have to do is to calculate an angle between time 00:00 and a line which goes though middle of the clock and a…
Arek S
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Finding the sides of Right Triangle when only angles are given

I have a question in which a Right angle triangle is given, one of the angle is 50 degree. Since it is a right angle therefor other two angles are 90degrees and 40degrees. The perpendicular of this triangle is equal to x, while the base of the…
Sufiyan Ghori
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Can you find the the various values of a non 45-45- 90 triangle if only given hypotenuse and right angle?

I'm working on some homework. With a simple yes or no if you have a right triangle ABC with B being the 90 degree angle and not a 45-45-90 triangle and you have the value of the hypotenuse and the right angle can you find... the lengths of both AB…
Jessica M.
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Guessing the nature of a triangle if one angle is 60 degrees

In triangle ABC, AB=12cm, angle B=60 degrees, the perpendicular from A to BC meets it at D. The bisector of angle ABC meets AD at E. Then E divides AD in the ratio $3:1,6:1,1:1,2:1$? I assumed it be an equlateral triangle. So, median, altitude and…
aarbee
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How to identify opposite and adjacent parts of right triangle

If you have a right triangle and both the opposite and adjacent sides have values of ex.10 or the same value. How do you determine which side is the opposite and which is the adjacent if they are both the same length? For example, are the opposite…
Jessica M.
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height and bisector in a right triangle

We have right angle $ABC$ where $AB$ is hypotenuse, and angle bisector $CD$ we know that $AB=c$, $CD=u$. Express height depending on the $c, u$, and what is the condition between $c,u$ that the triangle $ABC$ exist? I have some problems here I…
Mark
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