8.4 Circles, SPM Practice (Short Questions)


8.4 Circles, SPM Practice (Short Questions)
Question 9:
In figure above, ABC is a tangent to the circle centre O at B. AED is a straight line.
Find the value of y.

Solution:
ABO = 90o
BOE = 2 × 40o = 80o
In quadrilateral AEOB,
AEO = 360ABO  BOE – 35o
= 360– 90o – 80o – 35o = 155o
y o + AEO = 180
y o + 155o = 180o
y o = 180o  – 155o
y o = 25


Question 10:


In figure above, ABC is a tangent to the circle centre O, at point B.
The value of x is

Solution:
OBC = 90
BOD = 2 × 50o = 100o
In quadrilateral BODC,
xo = 360BOD OBC – 120o
= 360– 100o – 90o – 120o
= 50