Answer:
The value of a is 63° and the value of b is 27°
Step-by-step explanation:
In the given figure
∵ OA, OB, and OC are radii of the circle O
→ The radii of a circle are equal
∴ OA = OB = OC
In Δ AOC
∵ OA = OC
∴ Δ AOC is an isosceles triangle
→ Base angles of the isosceles triangle are equal
∵ ∠OAC and ∠OCA are the base angles of the triangle
∴ m∠OAC = m∠OCA
∵ m∠OAC = a°
∴ m∠OCA = a°
→ The sum of angles in any triangle is 180°
∵ a° + a° + m∠AOC = 180°
∵ m∠AOC = 54°
∴ a° + a° + 54 = 180°
→ Add the like terms
∴ 2a° + 54 = 180°
→ Subtract 54 from both sides
∴ 2a° = 126°
→ Divide both sides by 2
∵ m∠OAC = m∠OCA = 126 ÷ 2
∴ a° = 63
∴ The value of a is 63°
In ΔBOC
∵ OB = OC
∴ Δ BOC is an isosceles triangle
→ Base angles of the isosceles triangle are equal
∵ ∠OBC and ∠OCB are the base angles of the triangle
∴ m∠OBC = m∠OCB
∵ m∠OBC = b°
∴ m∠OCB = b°
∵ ∠AOC is an exterior angle of ΔBOC at the vertex O
→ The measure of the exterior angle equals the sum of the measure
of the opposite interior angles to this vertex
∵ ∠OBC and ∠OCB are the opposite interior angle of ∠AOC
∴ m∠OBC + m∠OCB = m∠AOC
→ Substitute their measures
∵ b° + b° = 54°
→ Add the like terms
∴ 2b° = 54
→ Divide both sides by 2
∴ b° = 27
∴ The value of b is 27°
3: