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phoenix9801
- Master | Next Rank: 500 Posts
- Posts: 190
- Joined: Thu Jan 14, 2010 8:29 pm
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1. internal angle a = 15
internal angle b = 180-80 = 100
ext angle c = int a+ int b = 115
2.90+x+x = 180 => x = 45
3.90+x+35 = 180 => x = 55




















