Respuesta :

nap14hockey

The three interior angles of any triangle add to 180 degress.  Therefore,


180-(120 + 40) = the third angle.


So, 20 is the third angle

tramserran

Answer: 20°

Step-by-step explanation:

1. B = 120°, C = 40°             1. Given

2. A + B + C = 180°             2. Triangle Sum Theorem

3. A + 120° + 40° = 180°      3. Substitution Property

4. A + 160° = 180°                4. Simplify (added like terms)

5. A = 20°                            5. Subtraction Property of Equality

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