Geometry Techniques to Determine Missing Angles
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All Together Now
Techniques to Determine Missing Angles

 

 Sometimes we have parallel lines and triangles together.

 We might have something like this ...
 

 

 
 Example:
 Find the measure of all of the angles ...
 

 

 
 Step 1)
 Forget about the triangle for a minute
 and figure out the angles in the parallel lines.
 First put in all the 70 angles.
 

 

 
 Step 2)
 Put in the other angles where the lines cross.
 

 A + B + 70 + 70 = 360

 A + B = 220

 A = B

 2A = 220

 A = 110    B = 110

 

 

 
 Step 3)
 Now figure out the angles in and near the triangle
 

 

 
 so the whole thing looks like this:
 

 

 

   copyright 2005 Bruce Kirkpatrick

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