8.4 Circles, SPM Practice (Short Questions)
In figure above, ABC is a tangent to the circle centre O at B. AED is a straight line.
Find the value of y.
∠ABO = 90o
∠BOE = 2 × 40o = 80o
In quadrilateral AEOB,
∠AEO = 360o – ∠ABO – ∠BOE – 35o
= 360o – 90o – 80o – 35o = 155o
y o + ∠AEO = 180o
y o + 155o = 180o
y o = 180o – 155o
y o = 25