If it’s under 90 make a acute angle of it 90 make a right angle if it’s over 90 make a obtuse angle
For this case, we have that by definition, the circumference of a circle is given by:

Where:
d: Is the diameter of the circle given by 2r, that is, twice the radius.
If we have a circle with a diameter equal to 8cm, then the circumference is given by:

ANswer:
Option C

Answer:
b
Step-by-step explanation:
The answer is b
it's a special triangle
Maybe you can study it or figure out a trick. I usually study with my sibling, but if you don't have any, friends or other family. I am sure they won't mind. Also, maybe making flashcards, those work well.
Also, you can print out worksheets and make your brain remember. PRACTICE!