Answer:
m∠A is 89°
Step-by-step explanation:
By circle theorem, two or more inscribed angles subtended by the same arc are equal
Therefore, from the diagram, we have;
Angle (5·x - 1)° and angle (4·x + 17)° subtends the same arc DC
∴ (5·x - 1)° = (4·x + 17)°
We can write the angles as follows since they are both in degrees
(5·x)° - 1° = (4·x)° + 17°
(5·x - 4·x)° = 17° + 1°
x = 18°
m∠A = (5·x - 1)°
∴ m∠A = (5 × 18 - 1)° = (90 - 1)° = 89°
m∠A = 89°.
