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How to you find the value of missing angels in a triangle?

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How to you find the value of missing angels in a triangle? I looked it up on google and there was this law thing but I'm in applied math and my teacher said something about z and c patterns

Jun 18, 2015

#3
+4682
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Rule One: All triangles add up to 180º.

REMEMBER:

Equilateral Triangle: All sides are the same : 60 + 60 + 60 =180

Isosceles Triangle: Two sides the same : E.G. 50+ 50 + 80 = 180

Scalene Triangles: All sides different : E.G. 50+ 30 + 100

Jun 19, 2015

#1
+5

The method used depends on the situation:

▪ The "Z" method is simply if you have two parralel lines, and are joined by a straight line (Either in a Z shape or a _/‾ shape) the 'inside' angle at either side will be identical, and the 'outside' angle at either side will also be identical. This will rarely apply to triangles however.

▪ If you know 2 angles already, then you can use the fact all 3 angles of a triangle add together to equal 180. So, 180 subtracted by the other two angles will give you the third angle.

This is the simplest and most often needed.

The rest I am going to mention needs some work with forumlae. Depending what level of mathmatics you are working with, these may or may not be relevant at all.

▪ If you know the length of a side opposite a known angle, you can work out the value of any other angle as long as it is opposite to another known side using the "Sine" rule.

Re-arranged this can be used as:

▪ If you know 2 side lengths but the known angle is not opposite either, you can use the "Cosine" rule to work out the third side. From there you can use the Sine rule to work out the other angles.

This rule can also be used to find any angle if you know all 3 sides, by re-arranging the forumla to:

Jun 19, 2015
#2
+95177
+10

https://www.mathsisfun.com/geometry/parallel-lines.html

alternate angles make a z shape

Co-interior angles make a C shape

and

Corresponding angles make an F shape.

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If you scroll down on this one it willshow you the Z, C and the F very clearly :)

http://passyworldofmathematics.com/angles-and-parallel-lines/

Jun 19, 2015
#3
+4682
+10

Rule One: All triangles add up to 180º.

REMEMBER:

Equilateral Triangle: All sides are the same : 60 + 60 + 60 =180

Isosceles Triangle: Two sides the same : E.G. 50+ 50 + 80 = 180

Scalene Triangles: All sides different : E.G. 50+ 30 + 100

MathsGod1 Jun 19, 2015