Step-by-step explanation:
Example 7
Join C to B to form BC, thereby creating ∆ ABC
OC is the radius of the circle (O is the center of the circle).
AD is the tangent to the circle at point C
When a radius of a circle meets with a tangent of the same circle, the angle between them is 90°
<ACB = <ACO = 90°
<ABC = 180 - (<ACB + <BAC)
= 180-(90+40)
= 50
Look closely,
<ABC = x = 50°
.
.
Example 8
Do same as Example 7
Join O to B to form OB, which is the radius of the circle.
<ABO= 90°
< BOA = 50°
<OAB= x+25= 180-(90+50)
x+25= 40°
x = 15°
