Question 79709: REVIEW
30: The radius of a Circle O is 4, if radii OA and OB form 90o angle, AB = ?
Answer by doctor_who(15)   (Show Source):
You can put this solution on YOUR website! There are 360o in a circle, so if the angle between OA and OB is 90o then you've cut a slice exactly equal to a quarter of a circle. (because 360 = 90 X 4)
The formula for the whole circumference of the circle is pi X radius squared
.. which is pi X 4 X 4 = 16 X pi.
You've got exactly a quarter of that, so AB is 4 X pi. (ANSWER)
If you need an exact answer, work it out on a clculator, knowing that pi = 3.14159 (approximately)
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