Step 1: Find the angle between the tangent and chord CD.
The exterior angle formed by the tangent and chord CD is 146∘. The angle inside the circle, formed by the tangent and chord CD, is supplementary to this exterior angle.
Angle(tangentatD,chordCD)=180∘−146∘=34∘
Step 2: Apply the Alternate Segment Theorem to find angle b.
The Alternate Segment Theorem states that the angle between a tangent and a chord through the point of contact is equal to the angle in the alternate segment.
The angle between the tangent at D and chord CD is 34∘. The angle in the alternate segment subtended by chord CD is ∠CAD.
Therefore, ∠CAD=34∘.
Since angle b is ∠CAD, we have:
b=34∘
Step 3: Use the property of equal chords to find angle c.
The chords AD and CD are marked with single dashes, indicating they are equal in length. This means that △ADC is an isosceles triangle.
In an isosceles triangle, the angles opposite the equal sides are equal.
So, ∠ACD=∠CAD.
Since ∠CAD=b=34∘, then ∠ACD=34∘.
Since angle c is ∠ACD, we have:
c=34∘
Step 4: Relate the central angle a to the inscribed angle c.
Angle a is the central angle ∠AOD. Angle c is the inscribed angle ∠ACD. Both angles subtend the same arc AD.
The central angle subtended by an arc is twice the inscribed angle subtended by the same arc.
So, a=2×∠ACD.
a=2×c
a=2×34∘
a=68∘
The angles are:
a=68∘
b=34∘
c=34∘