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triangle.md

@@ -1,6 +1,6 @@
 # Triangle
 
-Triangle is a three sided [polygon](polygon.md), one of the most basic [geometric](geometry.md) shapes. It is a [convex](convex.md) shape. Furthermore it is a 2-[simplex](simplex.md), i.e. the simplest ["shape composed of sides"](polytope.md) in [2 dimensions](2d.md). Triangles are very important, they for example help us compute [distances](distance.md) or define functions like [sine](sin.md) and [cosine](cos.md) (see [trigonometry](trigonometry.md)).
+Triangle is a three sided [polygon](polygon.md), one of the most basic [geometric](geometry.md) shapes. It is a [convex](convex.md) shape and a 2-[simplex](simplex.md), i.e. the simplest ["shape composed of sides"](polytope.md) in [2 dimensions](2d.md). Needles to say triangles are very important, they for example help us compute [distances](distance.md) or define [functions](function.md) like [sine](sin.md) and [cosine](cos.md) (see [trigonometry](trigonometry.md)).
 
 { In my favorite book [Flatland](flatland.md) triangles represent the lowest class of men with isoscele triangles being the lowest as they are most similar to [women](woman.md) who are just straight [lines](line.md). ~drummyfish }
 
@@ -21,7 +21,7 @@ Triangle consists of three [vertices](vertex.md) (usually labeled *A*, *B* and *
 
 **Similar triangles** are triangles that "have the same shape" (but may be of different sizes, positions and rotations). Two triangles are similar if the lengths of corresponding sides have the same ratios, or, equally, if they have the same inside angles. E.g. a triangle with side lengths 1, 2 and 3 is similar to a triangle with side lengths 2, 4 and 6. This fact is very useful in some geometric computations as it can help us determine unknown side lengths.
 
-**Equilateral triangle** is a triangle whose sides have the same length, which means all its angles are also equal (60 degrees, pi / 3 radians). Equilateral triangles are of course all similar to each other. An **isoscele triangle** is a triangle with two sides of the same length. We can also distinguish acute and obtuse triangles (obtuse having one angle greater than 90 degrees).
+**Equilateral triangle** is a triangle whose sides all have the same length, which means all its angles are also equal (60 degrees, pi / 3 radians). Equilateral triangles are of course all similar to each other. An **isoscele triangle** is one with two sides of the same length. We can also distinguish acute and obtuse triangles (obtuse having one angle greater than 90 degrees).
 
 In a triangle there exist two important types of helper line segments: **median** and **altitude**. Median goes from a triangle's vertex to the opposite side's center. Altitude goes from a vertex to the opposite side in a perpendicular direction to that side. Each triangle has three medians and three altitudes.
 
@@ -45,7 +45,7 @@ Some basic facts, features and equations regarding triangles are following (bewa
 - Triangle vertices always line in a single [plane](plane.md) -- it's pretty clear but good to realize e.g. in 3D graphics, every face in a triangle mesh will always have a clearly defined normal etc.
 - ...
 
-In non [Euclidean](euclidean.md) ("crazy") geometries triangles behave weird, for example we can draw a triangle with three right angles on a surface of a [sphere](sphere.md) (i.e. its angles add to more than 180 degrees). This fact can be exploited by inhabitants of a space (e.g. our [Universe](universe.md)) to find out if they in fact live in a non Euclidean space (and possibly determine the space's exact [curvature](curvature.md)).
+In non [Euclidean](euclidean.md) ("crazy") geometries triangles behave weird, for instance we can draw a triangle with three right angles on a surface of a [sphere](sphere.md) (i.e. its angles add to more than 180 degrees). This fact can be exploited by inhabitants of a space (e.g. our [Universe](universe.md)) to find out if they in fact live in a non Euclidean space (and possibly determine the space's exact [curvature](curvature.md)).
 
 Constructing triangles: if we are to construct (draw) triangles with only partial knowledge of its parameters, we may exploit the above mentioned attributes to determine things we don't explicitly know. For example if we're told to construct a triangle with knowing only the lengths of the sides but not the angles, we can determine an angle of one side using the law of cosines at which point we can already draw all three vertices and just connect them. In other words just use your brain.
 
@@ -82,3 +82,8 @@ int pointIsInTriangle(int px, int py, int tp[6])
   return 1;
 }
 ```
+
+## See Also
+
+- [line](line.md)
+- [circle](circle.md)