1 1. As shown in the figure, which angle of 1 forms two straight lines with 2 angles, 3 angles and 4 angles? What angles are they?

Answer: (1) Angle 1 and Angle 2, Angle 3 and Angle 4 are all cut by the line segment DB, and they are all inscribed angles. (2) Angle 1 and Angle 2 are cut by line segment CB, Angle 3 and Angle 4 are cut by ray AE, Angle 1 and Angle 2 are ipsilateral internal angles, and Angle 3 and Angle 4 are isosceles angles.

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