Answer:
SAS postulate
Step-by-step explanation:
AD (common)
AC = BD (both are diameters)
Angle COD = Ange AOD (vertically opposite angles)
Angle CAD = Angle BAD (angle on the circumference is half the angle at the centre)
Therefore, ABD and DCA are congruent by SAS postulate
Hello,
Please, see the detailed answer in the attached files.
Thanks.
When solving these proportions we just remember when moving a number from one side to the other if it started in the numerator it ends up in the denominator and vice versa.
I'll do it in two steps here for teaching purposes; it's not too hard to go directly to the answer.



Step-by-step explanation:
You have miscopied the second equation as it contains a third variable B when there isn't a B in the answers.
Please correct it for assistance
Minus 3 from the 3 and the 18