# Geometry Missing Angles

1. Mar 6, 2013

### Ellieman

Find the missing angles in each of the following:

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2. Mar 6, 2013

### eumyang

Need to show an attempt of these problems. What is the difficulty here?

3. Mar 6, 2013

### Ellieman

Triangle: 180-129= 51
180-138= 42
A+51+42= 180
A= 180-51-42= 87 degrees

Regular Octagon: (8-2)180/8= 135 degrees

4. Mar 6, 2013

### Ellieman

I am not sure how to find the angles for the other problems

5. Mar 6, 2013

### eumyang

Are you familiar with this theorem?
You can use this for the top right and bottom right problem in your attachment.

Are you also familiar with supplementary angles?

6. Mar 11, 2013

### Ellieman

180-38-100= 42

a is corresponding to y
z is the alternate exterior angle to a
x is supplementary to a
105+x= 180
x= 75
z= 105

180-30-70= 80
< 3= 80
I am not sure how to solve for < E and < A

7. Mar 11, 2013

### Ellieman

120-180= 60

8. Mar 11, 2013

### eumyang

You were also given three pairs of parallel lines. Use that, and the theorem I quoted in post #5, to find angles E and A.