1. **Problem Statement:** Given two overlapping circles with points A, B on the larger circle and points D, O on the smaller circle, and given angles 90° at D, 42°, 30°, and 120°, find the sizes of angles CBD, ODB, BAD, ABC, and ODA.
2. **Key Information and Rules:**
- Angle at D is 90° (right angle).
- Angles around a point sum to 360°.
- Angles in a triangle sum to 180°.
- Angles subtended by the same chord in a circle are equal.
3. **Find angle CBD:**
- Angle CBD is adjacent to angle 42° and 90° at D.
- Since angle at D is 90°, and angle at the top right is 42°, angle CBD = 90° - 42° = 48°.
4. **Find angle ODB:**
- Angle ODB is inside the smaller circle at point D.
- Given angle at D is 90°, and angle near D inside smaller circle is 30°.
- Using triangle sum: angle ODB = 180° - 90° - 30° = 60°.
5. **Find angle BAD:**
- Angle BAD is on the larger circle.
- Given angle between A and B is 120°.
- Since angle BAD and 120° are subtended by the same chord, angle BAD = 120°.
6. **Find angle ABC:**
- Angle ABC is on the larger circle.
- Using triangle sum in triangle ABC: angles BAD + ABC + BAC = 180°.
- Given BAD = 120°, and assuming BAC = 30° (from given 30° near D), then ABC = 180° - 120° - 30° = 30°.
7. **Find angle ODA:**
- Angle ODA is at point D inside smaller circle.
- Using triangle sum in triangle ODA: angles ODA + OAD + AOD = 180°.
- Given OAD = 42°, AOD = 90°, then ODA = 180° - 42° - 90° = 48°.
**Final answers:**
- a) Angle CBD = $48^\circ$
- b) Angle ODB = $60^\circ$
- c) Angle BAD = $120^\circ$
- d) Angle ABC = $30^\circ$
- e) Angle ODA = $48^\circ$
Circle Angles E7Cc6C
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