Question

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Answer 1

Notice that:

`\measuredangle ABC=\measuredangle1+\measuredangle DBC`

Solving for angle 1 we get:

`\measuredangle1=\measuredangle ABC-\measuredangle DBC`

Substituting the measure of angles ABC and DBC we get:

`\begin{gathered} \measuredangle1=135^(\circ)-75^(\circ) \\ \measuredangle1=60^(\circ) \end{gathered}`

The measure of ∡1 is 60 degrees.