An equilateral triangle ABC and a scalene triangle DBC are inscribed in a circle on same side of the arc. What is \angle BDC equal to?
- A. 30^\circ
- B. 45^\circ
- C. 60^\circ ✓
- D. 90^\circ
Correct Answer: C. 60^\circ
Explanation
Angles subtended by the same arc (or chord BC) at any point on the remaining part of the circle are equal. Therefore, \angle BDC = \angle BAC. Since ABC is an equilateral triangle, \angle BAC = 60^\circ. Hence, \angle BDC = 60^\circ.
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