Example 1

Calculate the magnitude of the angle [[$ \alpha $]] .


The angles [[$ 120° $]] and [[$ \alpha $]] are adjacent angles, which means that [[$ \alpha = 180° -120° = 60° $]].

Example 2

Deduce the magnitudes of the unknown angles.

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[[$ \begin{array} \\ \beta = 110° &\text{Angles} \beta \text{ and 110° are opposite angles.}\\ \alpha = 180° - 110° = 70° &\text{The sum of the adjacent angles is } 180°.\\ \gamma = \alpha = 70° & \text{Angles }\gamma \text{ ja } \alpha \text{ are opposite angles.} \\ \end{array} $]]​