Answer:
1. 51°
2. 40°
3. 65°
4. 60°
Explanation:
The sum of the angles in a triangle is 180°. We can use the angles given to find the missing angle.
1. 51°
42+87+x=180
129+x=180
x=51
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2. 40°
110+30+x=180
140+x=180
x=40
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3. 65°
20+95+x=180
115+x=180
x=65
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4. 60°
60+60+x=180
120+x=180
x=60